Added connection settings update and fixed bugs

* Removed 0.11 release due to ugly bugs, bumped version to 0.12
* There are now 4 methods of updating the connection settings; 3 global and
  1 on a per-model basis.
* Connection options are now documented in util
* Added ForeignModel column to reference other ORM columns
* Missing ManyToOne foreign keys will now no longer save an empty string
* Refactored a few bits
* Fixed .count() method on Query objects
* Fixed missing QueryError import in rom/index.py
* Fixed handling of limits in queries
* Fixed handling of cached entities in the session after .commit() but before
  entities fell out of scope
* Added more tests