Sep 23 2017

This release primarily motivated to demarcate compatibility with upcoming bazel 0.6.0.

• Renames all instances of set to depset.
• Changes idiom of list(set(deduplicate_me)) to depset(deduplicate_me).to_list()
• Improves output path calculation for generated protos when used as external workspaces (@Douglasreid)
• Improved support for python requirements (@mattmoor)
• New attribute importpath for go_proto_library
• Documentation update