Use listDatabases to get the totalSize of databases on disk for selecting the best shard to place the primary when enabling sharding on a new database.
Merge pull request #1029 from ankurcha/distribute_shards

made mongos choose primary shard based on data size estimates

This makes mongos distribute databases' primary shards properly.

#422
added CONTRIBUTORS file and added @ankurcha for #1029
Merge branch 'bugfixes/tokumx-1.4'