Add Messages class

[adamfr33man]

See Users, Websites or Conversations for an example of how to do this.
Branch off the i5-dont-flush-db unless that's been merged, that will have a TODO with where to instantiate the code and have an example of which API to call.

[johnsonreyliu]

added a small example to my branch - messages-branch. Not able to fully test it out until db auth is working