add chefspec tests
add travis support
convert mongodb_instance from definition into resource
factor different type instances into their own classes
Merge branch 'convert-to-resource' of github.com:josephholsten/mongodb-cookbook into convert-to-resource

Conflicts:
	.travis.yml
	Gemfile
	Rakefile
	definitions/mongodb.rb
	metadata.rb
	recipes/configserver.rb
	recipes/default.rb
	recipes/mongos.rb
	recipes/replicaset.rb
	recipes/shard.rb
	test/unit/default_spec.rb
	test/unit/mms-agent_spec.rb