[DO NOT MERGE] Ensure rs.conf() is run on the proper mongod process

Currently, rs.conf() can only be run on 127.0.0.1:27017.
When running a node in shardsvr mode, the mongod process
listens on port 27018, hence the rs.conf() check fails.

DO NOT MERGE IT YET UNTIL WE FIND A PUPPET WAY TO DO THAT.
SO FAR ITS JUST A DIRTY HACK TO GET ME GOING WITH MY END GOAL.
Add support for mongos configuration
Implement Sharding Support

This patch aims to support MongoDB sharding feature.

* Enable Sharding in MongoDB configuration file if enabled (disabled by
  default).
* Add a Type and a Provider to manage a MongoDB Shard resource.
* Add tests/sharding.pp to show an example of usage.
* Update the documentation about MongoDB Sharding usage.
* Unit tests for the new Type and the new Provider.

Conflicts:
	manifests/server.pp