Release 1.3.0 of bmv2

• ability to retrieve meter rate configuration through Thrift interface
• enable_swap can now be enabled for simple_switch when starting it
• tentative support for parser value set (no support for individual value masks so likely to evolve to some kind of ternary implementation)
• support for valid hidden fields for headers, so that ternary matching can be done on header validity
• updated googletest copy
• some minor other changes