Python3 Compatibility Issue

[stalinkay]

I'm getting the following stack trace on macOS High Sierra. See this question for a possible solution

Traceback (most recent call last):
  File "/usr/local/bin/powerline-shell", line 11, in <module>
    sys.exit(main())
  File "/usr/local/lib/python3.6/site-packages/powerline_shell/__init__.py", line 218, in main
    segment.add_to_powerline()
  File "/usr/local/lib/python3.6/site-packages/powerline_shell/segments/ruby_version.py", line 13, in add_to_powerline
    if os.environ.has_key("GEM_HOME"):
AttributeError: '_Environ' object has no attribute 'has_key'

[b-ryan]

Was fixed in #366

[stalinkay]

@b-ryan Thanks.