Details
Description
Some rebase'ing at $dayjob found that HBASE-18133 and HBASE-18135 never made it to any branch-2's.
There's no good reason that I can think of as to why we shouldn't backport these (will make quotas and snapshots much more accurate). As memory serves me, they just were landing when we were branching for early 2.0.0 releases.
Let's get backports for HBASE-18133, HBASE-18135, and HBASE-20531 (and implicitly HBASE-20439 and HBASE-20440)