Add optional attribute_name to Field
Basic priority tests for name vs attribute_name
Create __repr__ generator

Since most of the class's __repr__ functions will just be dumps
of the attributes on the object, this reduces the duplication to
simplify specifying the list of attributes to include.
Fix format string for py26
Use repr_func for all classes

More verbose __str__ and __repr__ should simplify
tracking down bugs
Revert "Add optional attribute_name to Field"
This reverts commit 887d678b479a54bc1c1325a2181df798b5bd2b4a.

Initial commit was a bit hasty - need to figure out how
Field attr names map to table schemas, dynamo3 queries, etc.

Conflicts:
	flywheel/fields/conditions.py
	flywheel/model_meta.py
	flywheel/query.py