Support Bazel 0.7.0 with rules_scala.

[greggdonovan]

The latest version of rules_scala supports Bazel 0.7.0.

The master version of bazel-deps fails with Bazel 0.7.0:

gdonovan@3983:~/development/bazel-deps (master)$ bazel build //... && bazel test --test_output errors //... && bazel build src/scala/com/github/johnynek/bazel_deps/parseproject_deploy.jar && ./gen_maven_deps.sh generate -r `pwd` -s 3rdparty/workspace.bzl -d dependencies.yaml && git diff --exit-code
ERROR: /Users/gdonovan/development/bazel-deps/3rdparty/jvm/org/typelevel/BUILD:87:1: in scala_library rule //3rdparty/jvm/org/typelevel:macro_compat: 
Traceback (most recent call last):
        File "/Users/gdonovan/development/bazel-deps/3rdparty/jvm/org/typelevel/BUILD", line 87
                scala_library(name = 'macro_compat')
        File "/private/var/tmp/_bazel_gdonovan/6fcac0fd900f6c0d2558c506b5c338d2/external/io_bazel_rules_scala/scala/scala.bzl", line 662, in _scala_library_impl
                _lib(ctx, True)
        File "/private/var/tmp/_bazel_gdonovan/6fcac0fd900f6c0d2558c506b5c338d2/external/io_bazel_rules_scala/scala/scala.bzl", line 633, in _lib
                create_java_provider(ctx, scalaattr, jars.transitive_comp...)
        File "/private/var/tmp/_bazel_gdonovan/6fcac0fd900f6c0d2558c506b5c338d2/external/io_bazel_rules_scala/scala/scala.bzl", line 566, in create_java_provider
                java_common.create_provider(ctx.actions, java_toolchain = ctx...., <4 more arguments>)
Output artifact 'external/org_typelevel_macro_compat_2_11/jar/macro-compat_2.11-1.1.1-ijar.jar' not under package directory '3rdparty/jvm/org/typelevel' for target '//3rdparty/jvm/org/typelevel:macro_compat'.
ERROR: Analysis of target '//3rdparty/jvm/com/github/mpilquist:simulacrum' failed; build aborted: Analysis of target '//3rdparty/jvm/org/typelevel:macro_compat' failed; build aborted.
INFO: Elapsed time: 3.466s

This is part of the fix for BUILD_file_generator#25.

[johnynek]

👍