Get rid of mix and rebar2 and permanently move to rebar3

Also, it removes Elixir bindings for Hello and Hello.Clien. Now Elixir
code which uses them should have aliases for both modules:

    alias :hello, as: Hello
    alias :hello_client, as: Hello.Client

.travis.yml

@@ -3,20 +3,12 @@ before_install:
    - sudo apt-get install avahi-daemon libavahi-compat-libdnssd-dev
    - wget https://s3.amazonaws.com/rebar3/rebar3
    - chmod u+x ./rebar3
-language: elixir
-elixir:
-    - 1.2.6
-    - 1.3.2
+language: erlang
 otp_release:
-   - 18.3
-   - 19.0
+    - 18.0
+    - 18.3
+    - 19.0
+    - 20.0
+install: "true"
 script: 
-    - mix compile
-    - rm -Rf deps _build
-    - ./rebar3 update
-    - ./rebar3 compile
-    - rm -Rf _build
-    - rebar get-deps
-    - rebar compile 
-    - rebar ct skip_deps=true
-after_failure: "cat logs/raw.log"
+    - ./rebar3 do compile && ./rebar3 do ct && ./rebar3  coveralls send

rebar.config

@@ -1,29 +1,55 @@
-{erl_opts, [{parse_transform, lager_transform},
-        {d, debug}]}.
+{erl_opts, [{parse_transform, lager_transform}, {d, debug}]}.
 
-{plugin_dir, "deps/yang/rebar_plugins"}.
-{plugins, [rebar_yang_compiler]}.
+{plugins, [
+           coveralls,
+           {rebar3_yang_plugin, {git, "git://github.com/surik/rebar3_yang_plugin.git", {tag, "0.2.2"}}}
+          ]}.
+
+{provider_hooks, [
+                  {post, [{compile, {yang, compile}}]}
+                 ]}.
 
 {yang_opts, [
     {yang_dir, "test"},
     {yang_build_dir, "test/hrl"}
 ]}.
 
 {deps, [
-        {lager, ".*",         {git, "git://github.com/basho/lager.git", {branch, master}}},
-        {cowboy, ".*",        {git, "git://github.com/extend/cowboy.git", {branch, "1.0.x"}}},
+        lager, 
+        {cowboy, "1.1.2"},
+        hackney, 
+        jsx, 
+        hackney,
+        exometer_core,
+        {msgpack, "0.6.0"},
         {yang, ".*",          {git, "git://github.com/travelping/yang.git", {branch, "master"}}},
-        {hackney, ".*",       {git, "git://github.com/benoitc/hackney.git", {branch, master}}},
         {ex_uri, ".*",        {git, "git://github.com/heroku/ex_uri.git", {branch, master}}},
         {ezmq, ".*",          {git, "git://github.com/RoadRunnr/ezmq.git", {branch, "fix-socket-crash"}}},
-        {jsx, ".*",           {git, "git://github.com/talentdeficit/jsx.git", {branch, develop}}},
-        {msgpack, ".*",       {git, "git://github.com/msgpack/msgpack-erlang.git", {tag, "0.6.0"}}},
-        {dnssd, ".*",         {git, "git://github.com/benoitc/dnssd_erlang.git", {branch, master}}},
-        {meck, ".*",          {git, "git://github.com/eproxus/meck.git", {branch, master}}},
-        {exometer_core, ".*", {git, "git://github.com/Feuerlabs/exometer_core", "5fdd9426713a3c26cae32f644a3120711b1cdb64"}},
-        {coveralls, ".*",     {git, "git://github.com/markusn/coveralls-erl.git", {branch, "master"}}}
-       % {tetrapak_yang, ".*", {git, "git://github.com/travelping/tetrapak_yang.git", {branch, master}}}
+        {dnssd, ".*",         {git, "git://github.com/benoitc/dnssd_erlang.git", {branch, master}}}
        ]}.
 
+
+{profiles, [
+    {test, [
+        {deps, [meck]}
+    ]}
+]}.
+
+{overrides, [
+             {override, abnfc, [{erl_opts, [nowarn_export_all]}]},
+             {override, yang, [{plugins, [pc]}, 
+                               {provider_hooks, [{post, [{compile, {pc, compile}}, 
+                                                         {clean, {pc, clean}}]}]}]},
+             {override, dnssd, [{plugins, [pc]}, 
+                                {provider_hooks, [{post, [{compile, {pc, compile}}, 
+                                                          {clean, {pc, clean}}]}]}]},
+             {override, ex_uri, [{plugins, [rebar3_abnfc_plugin]},
+                                 {provider_hooks, [{pre, [{compile, {abnfc, compile}}]}]}]}
+            ]}.
+
 {cover_enabled, true}.
 {cover_export_enabled, true}.
+{coveralls_service_name, "travis-ci"}.
+{do_coveralls_after_ct, false}.
+{do_coveralls_after_eunit, false}.
+{coveralls_coverdata, "_build/test/cover/ct.coverdata"}.

rebar.config.script

@@ -1,36 +1,10 @@
 %% -*- erlang -*-
-YangPlugin = {plugins, [{rebar3_yang_plugin, {git, "git://github.com/surik/rebar3_yang_plugin.git", {branch, "master"}}}]},
-PCPlugin = [{plugins, [pc]}, {provider_hooks, [ {post, [ {compile, {pc, compile}}, {clean, {pc, clean}} ] }] }],
-AbnfcPlugin = [{plugins, [ {rebar3_abnfc_plugin, {git, "git://github.com/surik/rebar3_abnfc_plugin.git", {branch, "master"}}} ]},
-               {provider_hooks, [ {pre, [ {compile, {abnfc, compile}} ] }] }],
-
-HexDeps = [lager, cowboy, hackney, jsx, meck],
-
-OverrideYang = {override, yang, PCPlugin},
-OverrideDnssd = {override, dnssd,  PCPlugin},
-OverrideExUri = {override, ex_uri, AbnfcPlugin},
-Overrides = {overrides, [OverrideYang, OverrideDnssd, OverrideExUri]},
-
-code:is_loaded(rebar3) =:= false andalso code:load_file(rebar3),
-case erlang:function_exported(rebar3, version, 0) of
-    true -> 
-        CONFIG1 = lists:keyreplace(plugins, 1, CONFIG, YangPlugin),
-        NewDeps = lists:foldl(fun(Dep, Deps) ->
-                                      Key = case Dep of {K, _} -> K; K -> K end,
-                                      [Dep | lists:keydelete(K, 1, Deps)]
-                              end, proplists:get_value(deps, CONFIG1), HexDeps),
-        CONFIG2 = lists:keyreplace(deps, 1, CONFIG1, {deps, NewDeps}),
-        CONFIG2 ++ [ {provider_hooks, [{pre, [ {ct, {yang, compile}} ]} ]}] ++ [Overrides];
-    false -> 
-        case os:getenv("TRAVIS") of
-            "true" ->
-                JobId   = os:getenv("TRAVIS_JOB_ID"),
-                CONFIG1 = lists:keystore(coveralls_service_job_id, 1, CONFIG, {coveralls_service_job_id, JobId}),
-                {value, {plugins, Plugins}} = lists:keysearch(plugins, 1, CONFIG1),
-                lists:keystore(plugins, 1, CONFIG1, {plugins, Plugins ++ [rebar_coveralls]})
-                    ++ [{coveralls_coverdata, "logs/all.coverdata"},
-                        {coveralls_service_name, "travis-ci"},
-                        {plugin_dir, "deps/coveralls/src"}];
-            _ -> CONFIG
-        end
+CONFIG.
+case os:getenv("TRAVIS") of
+    "true" ->
+        JobId   = os:getenv("TRAVIS_JOB_ID"),
+        CONFIG1 = lists:keystore(coveralls_service_job_id, 1, CONFIG, {coveralls_service_job_id, JobId}),
+        JobId = os:getenv("TRAVIS_JOB_ID"),
+        lists:keystore(coveralls_service_job_id, 1, CONFIG, {coveralls_service_job_id, JobId});
+    _ -> CONFIG
 end.