Merge remote-tracking branch 'origin/feature/collections-performance' into feature/collections-performance
Build links for association proxy objects by inspecting the join object,
rather than by grabbing the id off of the target object. Ultimately,
this will eliminate the nead for eager loading most of the time.

Also, adopt a more efficient scheme for url generation for both resource
and view resources. The flask url_for method performs a lot of work that
needn't be repeatedly performed and short-circuiting that can provide a
great performance benefit.
Build relationship links using the available foreign key property,
otherwise use the target object as before.
Merge branch 'develop' into feature/collections-performance
Deferred column loading.
Merge develop
Merge branch 'develop' into feature/collections-performance

Conflicts:
	src/ggrc/models/directive.py
Eager loading for categorizations, renable publishing of categories and
assertions.
Merge branch 'develop' into feature/collections-performance
Some post merge fixes.
Turn off sql echo.
Fix endpoint name registration of views.
Merge branch 'develop' into feature/collections-performance
Merge pull request #166 from reciprocity/feature/collections-performance

A wide variety of performance tuning enhancements.