Add contributing and license files; edit readme
New illustrations
* change feeds
* dates and times
* sql to reql cheatsheet
* securing your cluster

Also added the table-joins image to the eq_join api page
Updated secure-cluster and changefeeds imgs
Updates based on feedback
Add index pages. Fixes #375 (again)
Fix typos; fixes #441
Added sharding_and_replication image
Add warning about getAll/orderBy limitation; fixes #405
Add info about Ruby DateTime troubleshooting; fixes #275
Merge branch 'issue-275-ruby-datetime'
Merge branch 'issue-419-add-contributing-file'
Fixes #419
Adding info about key length limitations
Update rethinkdb-vs-mongodb.md
Merge pull request #442 from rethinkdb/mg_quickfix

Update rethinkdb-vs-mongodb.md
Change formatting of generated Python docs
Merge branch 'issue-234-gen-python'
Fixes #234
Updating based on review
Merge branch 'issue-430-key-lengths'; fixes #430
Update pip install command

The old command failed to install the dependency. Running the command returned error:
```
Downloading/unpacking version==1.12.0-2
Could not find a version that satisfies the requirement version==1.12.0-2 (from versions: 0.1.0, 0.1.1)
Cleaning up...
No distributions matching the version for version==1.12.0-2
```
When asked about the issue via IRC @atnnn told me that the error is not OS dependent, so therefore I deiced to file a pull request for it.
Fix link to to_array