Fix offline doc build and test when you don't have a internet connection
First attempt at using astropy_helpers
Further setup.py work.
Start work on moving the docs over
Use https for astropy_helpers
Update astropy_helpers
Fix some doc weirdness with astropy_helpers.

Also make the mock import in conf.py only happen if it is needed.
Add astropy_helpers for relative import in conf.py

This assumes that astropy_helpers is in the root tree relative to the docs dir.
Changes to .travis.yml to try and make travis work
Attempt to change the astropy_helpers git module to point at my fork.
Make tests work using a modifed astropy_helpers
More updates to astropy_helpers
Add a test_helper file containing the dist ext.

The Distutils extension wraps our self_test function for
being run from setup.py.
Fix travis.yml.

* No more astropy git, just install after Cython
* Install xdist plugin
Update astropy_helpers submodule to 0.4.2
Add files to MANIFIEST and update version logic
update to master
Make tests work mostly ok.
Fix doc build and offline build
Some test fixes 1