Make a release for legacy python versions

[s-weigand]

Hi Oz,
since the merge of PR #49 the tests are broken, because pytests>=5. 0.0 dropped support for legacy python versions (namely in this case py27 and py34).
This PR will pass the tests and should be the release candidate for a minor version (i.e. 0. 6.0), so please bump the version after the merge.
To get up to date again, I will make a PR that drops all legacy code and make a note for users to use this release if they need support for older python versions.

P.S.: If you also stopped using py27 we could also upgrade bumpversion to bump2version, which is a fork of bumpversion which is still maintained and supports python 2+3.

[coveralls]

Pull Request Test Coverage Report for Build 148

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.4%) to 100.0%

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Totals
Change from base Build 147:	0.4%
Covered Lines:	356
Relevant Lines:	356

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💛 - Coveralls

[s-weigand]

Well the osx-py34 test is apparently failing, because anaconda isn't providing py34 for osx, anymore.
So it could be ignored, since with my next PR, py27 and py34 will be dropped anyway.