Kind of incidental to the actual purpose of this PR, but apparently when running 'astropy.test()' py.test creates this .cache directory. I normally just run setup.py test so I didn't notice this before.
As a temporary solution for #1112, add the lex/parsetab modules to the repository so we don't have to worry about whether or not they get installed.  Take code for generating them out of the setup_package modules.  Later we can worry about details of how to generate these, (or at least make it easy to regenerate if any changes are made to the parsers).
Merge pull request #1116 from iguananaut/issue-1112-temp

Temporary fix for #1112