Test framework (+ basic tests)
More tests, move to subdir, refactoring
Tests for legacy options and refactor.

- The legacy cmodel._{option} options have been covered by tests (so that
  we don't accidentally break current code).
- The new cmodel._connected_meta options have been covered by tests.
- The code has been refactored to work with the new options.
Warn when using legacy attributes
Remove legacy assignment to _connected_meta
Option should be proxy_model not proxy
Add tests for new api on the legacy proxy model
Remove useless loop (dead code)
Refactor ProxyMeta (legacy) to use the new options
Whitespace fixes
Tests for ORM save behavior
Basic tests for ORM get behavior
Serious refactoring of ConnectedMeta
Major refactoring of proxy models.

They are now created by subclassing the same ConnectedModel but by
setting the ConnectedMeta proxy attribute.

Also includes:
 - Tests
 - get_model() to retrieve a cmodel's model.
 - abstract option for cmodels
Merge branch 'feature/tests'