SERVER-15160 Don't stepdown on reconfigs unless necessary
SERVER-15535 Close all connections when reconfig results in a stepdown
SERVER-15535 Choose new sync source on reconfigs
SERVER-15236: Switch shardingtest setup back to MONGODB-CR.
Revert "SERVER-15198 Make scramIterationCount user configurable"

This reverts commit bf48f38 and 57e21a1.
SERVER-15521 Use maxWireVersion to set default shell auth mech
Merge remote-tracking branch 'upstream/master'