Fixed a log line in the master.

Review: https://reviews.apache.org/r/26198
Eliminated redundant resource accounting in the master.

Review: https://reviews.apache.org/r/26199
Added validation for missing ExecutorInfo::framework_id.

Review: https://reviews.apache.org/r/26200
Properly deprecated ReregisterSlaveMessage::slave_id.

Review: https://reviews.apache.org/r/26201
Introduced a version during slave (re-)registration.

Review: https://reviews.apache.org/r/26202
Removed redundant logging in the Master.

Review: https://reviews.apache.org/r/26203
Removed the need for Master::readdSlave.

Review: https://reviews.apache.org/r/26204
Cleaned up Master::addFramework.

Review: https://reviews.apache.org/r/26205