refs #895 Have meta collection use a custom serialized BSON as opposed to reusing the one
made for the partitioned collection. The one for the partitioned collection may
have a custom PK or secondary indexes. We don't want that for the meta collection
refs #895, support the existence of and writing to of secondary indexes.
Querying secondary indexes does not work properly yet.
refs #877
Shell modifications to make handling partitioned collections simpler:
add partitioned option to createCollection
add help text for oplog commands that manage space
add shell functions for adding/dropping partitions
fix bugs in ensureIndex of PartitionedCollection
fix nIndexesBeingBuilt()
fix bug in Collection::dropIndexes that affects partitioned collections with secondary indexes
fix bugs in appendPartition related to adding a partition to a collection with multiple indexes
add test,
change cursor type for secondary indexes so tests can distinguish