BUMP 2.7.1
post 2.7.1
SERVER-13760 Do not call dateToISOString if date is not formatable
SERVER-12803: Use CR/LF in log files on Windows
Revert "SERVER-8192 rewritten V1 btree key generation"

This reverts commit 441b3c183c76399f248205989dec757708601394.
Merge remote-tracking branch 'upstream/master'