RUBY-583: enable auth for tests
RUBY-583: add ability to run clusters with auth

This previously was failing as the ruby Process#spawn method was closing
the STDOUT file descriptor. Mongod as of (2.4.2) expects for STDIN and
STDOUT to be the first two file descriptors as the logging system
subsequently tries to reopen and reroute those hardcoded FD values.

You can read more about the issue here:

https://jira.mongodb.org/browse/SERVER-9362
RUBY-584 fixing unit tests that require a mongodb connection
minor: remove jruby gem deprecations
minor: restoring travis config from before branching changes
RUBY-583: fix for first admin user on MongoDB 2.2
RUBY-590: remove RSpec as part of cleanup
When reusing a manager after calling close and connect, make sure to re-set the associated thread_local to avoid an error