Add some Astropy-affliated packages

This adds several packages which use the astropy-helpers package.
The 'ah_bootstrap.py' code used is a little problematic since it:
1. Tries to get it's own copy of astropy-helpers from pip
2. Even when bundled, breaks EasyInstall's sandbox when making an egg package out of astropy-helpers
3. All this is overkill just to make sure that 'import astropy_helpers' works

I sed out the call to the bootstrap script and just make the packages depend on the installed version of astropy-helpers.
All ebuilds are ready for releases or -9999, but only ccdproc has some non-git releases. I intend to package up astroquery
in another pull request.

Note that these all depend on astropy-0.4 or astropy-0.4.1 being in the main tree.