Added support for NonQuery to get affected rows

- Added support for free text sql statements with optional params which
allows the called to get the number of affected rows. This should be
usable across all databases since it's using the standard
ExecuteNonQuery from IDbCommand.
- Added unit tests for the functionality
Renamed to ExecuteNonQuery to improve readability

- Refactored NonQuery to ExecuteNonQuery so that the implicit meaning of
the method translates in a better understood API.
Merge pull request #304 from devrios/master

Added support for NonQuery to get affected rows