Mongo server helper, read host and port from pinned pool.
RUBY-1250 - Helpers for server helper, silence output, use new interface.

Convert the tests to use the new server helpers. Extract common methods for
servers and replica sets to a helper. Turn off output unless MONGO_DEBUG is set.
RUBY-1250 - Call count of 1 is the default.
RUBY-1250 - Include instance metrics for single server operations.
RUBY-1250 - Guard for missing connection, use connection host/port for ismaster.
Run tests with replica sets.
Test drive mongo server.
RUBY-1250 - Make directories, start and stop processes.
Start and stop are chainable, include fileutils.
Only stop if we have a pid file.
Wait for start to change running? to true, wait for stop to make running? false.
Mongo server count returns the total number of running mongod processes.
Count children only counts mongod processes spawned by MongoServer.
Stop removes pid file, wrap Process.kill in rescue.
Use MongoServer#port_file_path, test removal of pidfile, manually release ports.
Refactor tests to use MongoServer.count, change local for next port test.
Test replica set flags.
Add mongo and bson_ext development dependencies, add license.
Create a client when the server starts, ensure that test process gets cleaned up
Add ping to get server status, clear client on stop.