Fix ping, add docs, added invites to lobby, added concept of offline vs online

- Doc changes to readme
- Fixed issue where ping call was using server sessions (derp)
- We now EVERY ip a user logs in under
- More user helper methods
- Added ability to invite online friends to lobby
- Fixed lobby template for new invite method
- Fixed bug accepting friend invites
- Added call to get a the users friends
- Added call to invite user to lobby
- Added (untested) code to worker to handle timeouts of users in lobbies