Revert "SERVER-15557 disallow setting of configuration options for non-active storage engine"

This reverts commit cf1c4bb5a9da98ec831ff0a30ae78abe81e1d1b0.
SERVER-14462 Fix all cases where client is null when we are creating an
OperationContext
SERVER-14462 Make db.currentOp report the currently held locks from the Lock Manager
SERVER-13635 disallow NULL entries in KVDatabaseCatalogEntry::_collections
Revert "SERVER-14462 Make db.currentOp report the currently held locks from the Lock Manager"

This reverts commit 1ae3facefbfdb05d3369576611eb96fb1a303815.
SERVER-14462 Make db.currentOp report currently held locks from Lock Manager
Merge branch 'master' of https://github.com/mongodb/mongo into tokuft