HBASE-11839 TestRegionRebalance is flakey
HBASE-11919 Remove the deprecated pre/postGet CP hook.
HBASE-11921 Minor fixups that come of testing branch-1 (Stack)
HBASE-11909 Documented how to find the current number of
 regions and why the numbers in the UI might not agree with hbck output
Note on bucketcache needs 0.98.6
HBASE-11923 Potential race condition in RecoverableZookeeper.checkZk() (Lars Hofhansl)
HBASE-11721 jdiff script no longer works as usage instructions indicate

* Add L argument to the curl pull of JDiff to handle following redirects.
* Change how Git repos are cloned to reflect how shallow clones work
  now.
* Change arguments to support BSD sed (i.e. on Mac OS X).
* chmod +x on the script.

Signed-off-by: Jonathan M Hsieh <jmhsieh@apache.org>