SQL support for delete and embedded resources

I have added support for DELETE methods and embedded resource to the SQL extension although I think there is room for improvement in the implementation for embedded resource.

I expanded the tests for SQL to include the DELETE tests and support nearly every test case covered by the Mongo tests. I'm not making an effort to support the Mongo query syntax so I have deleted those tests from the test suite for SQL.

Work In Progress:
- Support for POST and PATCH
- Lots of code repetition in the tests, working on making them DRY