Revert "Add services for sending and receiving messages."

This reverts commit 2a4b8c7751e1ad2ca7a9fc46ffd3be83b9a3025c.
Make user_answer_preference hookable.
Whitespace fixes.
Much work on messaging.
Fixing merge issues.
Fixing refactoring errors.
Fix space.
Entity API doesn't like empty arrays.
Revamped auth a bit.
Improved service call error handling a tad.
Send message implementation.
Show messages the right place on helper.
Added documentation.