Refactor, code clean and delete request support
Support for delete, nested and embedded resources
Expanded tests for get and delete for SQL

The tests for the GET and DELETE methods for the SQL extensions covers
nearly all test cases in their Mongo counterpart. Removed tests for
Mongo query syntax as it’s not supported by the SQL extension
Switched to str_to_date in parser
Kicked off unit testing SQL extension parts
Merge branch 'sqlalchemy' of github.com:dedalusj/eve into dedalusj-sqlalchemy