Pdpinch/documentation updates

WIP. Not ready to merge yet. 

@cgee or @bdero can you review the installation instructions, esp. part 3:

https://github.com/mitodl/edx-sga/blob/pdpinch/documentation-updates/README.rst#installation
I added more explicit instructions about how to add sga to requirements.

I haven't had to add it to OPTIONAL_APPS (that I'm aware of at least). How is that different than setting ALLOW_ALL_ADVANCED_COMPONENTS to true?

On Oct 24, 2014, at 9:59 AM, Carson Gee <notifications@github.com> wrote:

> I think this should be more specific. It should be added with -e git+https://github.com/mitodl/edx-sga@release#egg=edx-sga to requirements/edx/github.txt and added to lms/envs/common.py and cms/envs/common.py in the OPTIONAL_APPS list.
>