Refactor and simplify mongo_protocol
Replace mongodb.app with a mongodb.app.src[C
Cleanup rebar.config and update the bson dependency to use the soundrop fork
Fix a compilation warning in mongo_protocol
Rename mongodb_app into mongo_app and add mongo_sup
Rewrite the mongo connection handling
Cleanup mongo_connection:request/3
Rewrite the mongo module
Add mongo_id_server

The id server is responsible for generating request ids and object ids
to be used in the mongo and mongo_connection modules.
Add a supervisor for cursors
Rewrite the cursor to use a plain gen_server
Cleanup the mongo module
Use the id server in mongo_connection
Remove the unused replica set module
Remove the unused mvar module
Fix the reply parsing in mongo_connection

The mongodb protocol is not only using little endian encoding, but it also
include the prefix length in the prefix encoded payloads.
Fix the handling of the stop request in mongo_connection
Fix the starting of cursors in mongo_sup
Improve the mongo_connection type specs
Fix the return value for mongo_cursor:create/6