Removed some obsolete code for handling tag_svn_revision

git-svn-id: http://svn6.assembla.com/svn/pyfits/trunk@2077 ed100bfc-0583-0410-97f2-c26b58777a21
This adds a check on the validity of the README and CHANGES rst, per the request in #196. Also removes some obsolete code for checking tag_svn_revision (this will have to be kept in for the older release branches, however).

git-svn-id: http://svn6.assembla.com/svn/pyfits/trunk@2078 ed100bfc-0583-0410-97f2-c26b58777a21
This should fix the issue with the version/date regexp.

git-svn-id: http://svn6.assembla.com/svn/pyfits/trunk@2079 ed100bfc-0583-0410-97f2-c26b58777a21
Should fix the release_version issue. Turns out I just had a typo in the entrypoints map.

git-svn-id: http://svn6.assembla.com/svn/pyfits/trunk@2080 ed100bfc-0583-0410-97f2-c26b58777a21
Uses the [zest.releaser] section in setup.cfg instead of entry_points.  This of course requires some fairly recent version of zest.releaser (I forget exactly what version this was added in) but I'll figure that out and document it once I get around to documenting the release procedure.

git-svn-id: http://svn6.assembla.com/svn/pyfits/trunk@2081 ed100bfc-0583-0410-97f2-c26b58777a21
Started on the developer documentation for PyFITS (most of it just links back to Astropy's developer guide which applies more or less to pyfits as well) and added what I think is a mostly accurate release procedure (though I'll have to do the next release from my own documentation and take notes on how well it actually matches up).

git-svn-id: http://svn6.assembla.com/svn/pyfits/trunk@2082 ed100bfc-0583-0410-97f2-c26b58777a21