SERVER-16200 Eliminate a redundant strlen in ThreadSafeString
SERVER-16200 Use unordered container to track operation contexts
SERVER-16200 Eliminate some strcpy/strlen when handling namespaces
SERVER-16185 Use system allocator by default on OS X
SERVER-16094 remove batch write command downconversion functionality from mongos v2.8
Merge remote-tracking branch 'upstream/master'