Replica Set and Sharded Cluster test fixes for narrowed localhost exception

This PR has changes to the replica set and sharded cluster tests to make them work with the narrowed localhost exception.

The most significant changes are in mongo_config, which requires authentication before running certain commands necessary for setting up the replica set / sharded cluster.

Jenkins is almost green on all tests, there are just a few hiccups:
https://jenkins.10gen.com/job/mongo-ruby-driver-emilys-fork/82/

TODO:
Replica set
	- (1 test pending) complex_connect_test
	- (2 tests pending) read_preference_test
	- (1 test waiting for RUBY-788) refresh_test
Sharded tests
	- (2 tests waiting for RUBY-788) basic_test