persistence of l2network & ucs plugins using mysql

persistence of l2network & ucs plugins using mysql
- db_conn.ini - configuration details of making a connection to the database
- db_test_plugin.py - contains abstraction methods for storing database values in a dict and unit test cases for DB testing
- l2network_db.py - db methods for l2network models
- l2network_models.py - class definitions for the l2 network tables
- ucs_db.py - db methods for ucs models
- ucs_models.py - class definition for the ucs tables
dynamic loading of the 2nd layer plugin db's based on passed arguments
Create, Delete, Get, Getall, Update database methods at - Quantum, L2Network and Ucs
Unit test cases for create, delete, getall and update operations for L2Network and Ucs plugins
pep8 checks done
branch based off revision 34 plugin-framework