Added python test instructions.
Moved js tests to js_test.
UserPair unit test.

*Fixed parameter order for zadd in UserPair.add.
*Fixed implementation of sorted set in FakeRedis.
*Wrote test for UserPair.add.
Added test for UserPair.get_record_logs
Prep for user tab pages.

* Username -> user ID
* Added TODOs.
* Added comment.