Upgraded to bazel 0.6.1

Enable cpu environments so we can drop the NO_BUILD_* files!!!

Change-Id: I904612c5dcc1a1cd285e160c0836b7249ab5ce72
diff --git a/tools/build_rules/ruby.bzl b/tools/build_rules/ruby.bzl
index 2c93596..cfab2e9 100644
--- a/tools/build_rules/ruby.bzl
+++ b/tools/build_rules/ruby.bzl
@@ -3,7 +3,7 @@
 ruby_file_types = FileType(['.rb'])
 
 def _collect_transitive_sources(ctx):
-  source_files = set(order='compile')
+  source_files = depset(order='postorder')
   for dep in ctx.attr.deps:
     source_files += dep.transitive_ruby_files
 
@@ -34,7 +34,7 @@
   )
 
   return struct(
-    files = set([executable]),
+    files = depset([executable]),
     runfiles = ctx.runfiles(collect_data = True),
   )