Teamcity-messages

- drop Python 3.4 support
- pylint: support pylint >= 2.3 by PetrWolf 215
- unittest: fix test hierarchy for subtests in tests with doc comments by throwable-one 221

- pytest: fix comparing asserts by ikonst 210
- Retry writes to stream on a EAGAIN IOError by morganwahl 213

- pylint: initial support by PetrWolf 171 200

- Correct supported python versions, description, keywords

- python: dropped Python 2.4, 2.5, 3.2, 3.3 support. Latest version to support them is 1.21
- python: supported Python 3.6, 3.7
- behave: initial support
- unittest: subtests support
- various unicode fixes
- nose, unittest: correctly capture stdout to provide better test output
- twisted: format twisted Failure objects by jackrobison
- various test infrastructure fixes by sambrightman
- flake8: correctly initialize options by sambrightman
- various fixes to use teamcity-messages code in JetBrains PyCharm IDE

- pytest: internal Error during test collection with pytest and teamcity-messages plugin 112
- nose: support capturing test output from successful tests, 113
- Fix possible error when joining bytes and unicode (Victor Makarov, https://github.com/vitek)