Migrating documentation from wiki to readthedocs

The work is not completed. But I wanted to show you what I've got so far, so we can avoid duplication of effort and to ensure we are in agreement about the new documentation. I don't want to make a patch bomb, that you disagree with.

The main changes in this is converting the wiki from markdown to restructured text. They've been upload as they are in their current state, so any changes to them will be easy to see in separate commits. And changes will be necessary, to ensure that when the new documentation is uploaded it is actually accurate.

Having documentation being versioned alongside the code sound awesome. I had thought it was bad we had the documentation split, but I had never realised that benefit to moving everything to readthedocs.

This is PR for issue  #173 

TODO List

- [x] Make enumerated numbers increment numbers
- [x] Add relative links. Ideally so it doesn't break if a file's title is changed.
- [x] Fix tables. Find or write a method to create the tables, because writing by hand seems both highly timeconsuming and brittle.
- [x] Make headings consistent. Multiple main titles in a file will both be shown/linked to when doing toctree.
- [x] Make changes so everything is within 80 chars
- [x] Make images scaled, in oauth one image goes off the left side.
- [x] Add content page links to sidebar
- [x] Update changelog to latest version.
- [x] Reuse code in README.rst and index.rst to prevent duplicating work and mismatching.
- [x] Import CHANGES.rst into documentation.
- [x] Update comment parsing to latest version.
- [x] Update the Configuration files to latest version
- [x] Update contributors guide
- [x] The old praw.rst is not linked to in any toctree. Figure out what to do with it
- [x] Upload new branch as a seperate package on readthedocs. Test it looks good.
- [x] Ensure there is a edit on github page link
- [ ] Update project. Test readthedocs update everything correctly.