Add some additional config options to ThriftServerConfig

Includes:
- set a custom executor
- set maximum # of connections

Ported from master branch revision ea5d3df6e73bcdf614e8e37ff8809b31d930f465
Allow binding custom thrift codecs by class

Ported from master branch revision 94f10e499816f922ec63c963f6f41dbe4bbfed2c