Add OmniAuth Documentation

Add GitHub OmniAuth docs

Google instructions

Google instructions

Merge master

Clean things up

Clean things up

Clean things up

Clean things up

Clean things up

Clean things up

Clean things up

Add Google and Twitter docs

Add screenshot

Add screenshot

Clean things up

Clean things up

Clean things up

Clean things up

Clean things up

Clean things up

Clean things up

Finalize current docs

Finalize current docs

Add existing user information

Add twitter

Add twitter

Add Twitter disclaimer

Add Twitter disclaimer

remove old doc

Remove unnecessary link

Revert omniauth provider format

Use omniauth again