fix #60 - Update models in a collection instead of creating new ones

The problem was that the "options" object (which is where we store a pointer to the store) was not being passed down into the .update() routine.
#62 - parse the response from .execute()
No longer warn if the raw siren object being parsed does not have self url.

Entity validation should happen at a whole different level
Merge pull request #61 from kiva/fix-60

Fix 60
Merge pull request #64 from kiva/issue-62

Issue 62
fix

 * make sure options are passed into Model.parse()
 * make sure {silent: x} options are passed along to .save()
bump v0.3.5