implement setup.py -gitXYZ version tagging

[ixcat]

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Implment improved setup.py version tagging

goal is to have:

• 'bare' N.N.N when running against git-tagged N.N.N repository
• tagged N.N.N-<git-commit> when running from source

in order to:

• easily identify non-release vs release installs
• more easily support from-source releases when needed

need to find a mechanism that works to provide this for:

• pip release installs from pypi
• git client checkout installs (e.g. git clone && pip install .)
• pip url installs
• dj 'download archive' from github installs (e.g. pip install . when user doesn't have git - downgrading tag to 'src' may be acceptable here for non-tagged-release case)

additionally, this may require (could be broken out into some phased approach):

• log table adaptation to support this adjustment (version field too short, should git tag be core or separate field)

If log table adjustment is bundled with change, this should be implemented against a N.N.0 release