Support PEP440 and "predicted release versioning" for "latest master"

[ceball]

Current python packaging tools and conda support PEP440.

Our projects already use a PEP440 release versioning scheme (e.g. 1.2.3), and autover already supports that.

We'd also like to be able make packages between releases, but autover's version format there does
not match PEP440. Based on discussion in #2, if git is v0.2.0-5-g85da374, then we'd like a package version of 0.2.1.dev5+g85da374. Some projects will make packages available for every commit to master, in which case 0.2.1.dev5+g85da374 will be "the 5th developmental release of 0.2.1" (see comments in #2 for more details).

See:

• PEP440 and "version always up to date" tests #11 where I have tried to add some tests for the version
• Get conda package version from setup.py. #10 where I try to get the conda package version from autover (so that a project does not have to compose/specify the version format in more than one place): https://travis-ci.org/ioam/autover/jobs/332058395#L1716

[jlstevens]

Thanks for working on those PRs.

As far as I know, selecting the PEP440 format for non-release versions (and making sure it works) is the last thing we need to do before autover can be used as intended. Having tests is a great way to go about this.

[jlstevens]

Just as a clarification, the release version format is already PEP440 as it is so simple - what we need to decide is the version format for other types of package e.g 'dev' versions or the 'nightlies' etc.

[ceball]

Yeah, sorry, I just added a comment about that: #8 (comment)

[jlstevens]

We found a PEP440 scheme we are happy with in #15. Other than adding the appropriate documentation about it it works. Closing.