Add Travis support

Added a .travis.yml, and made the various tweaks to support it.

.gitignore

@@ -2,3 +2,4 @@
 **/*.errors
 **/*.log
 .bin/
+**/*.coverprofile

.gitmodules

@@ -1,3 +1,3 @@
 [submodule "grammars-v4"]
 	path = grammars-v4
-	url = git@github.com:antlr/grammars-v4.git
+	url = https://github.com/antlr/grammars-v4.git

.travis.yml

@@ -0,0 +1,25 @@
+dist: trusty
+sudo: false
+
+language: go
+go:
+  - 1.8.x
+  - 1.9.x
+
+go_import_path: bramp.net/antlr4
+
+before_install:
+  # Tools
+  - go get github.com/go-playground/overalls
+  - go get github.com/mattn/goveralls
+  - go get golang.org/x/tools/cmd/cover
+
+  # Deps
+  - go get github.com/kylelemons/godebug/pretty
+  - go get github.com/antlr/antlr4/runtime/Go/antlr
+  - go get github.com/iancoleman/strcase
+
+
+script:
+  - $GOPATH/bin/overalls -project=bramp.net/antlr4 -covermode=count -debug
+  - $GOPATH/bin/goveralls -coverprofile=$GOPATH/src/bramp.net/antlr4/overalls.coverprofile -service=travis-ci