Sentry 1.5.0 has been branched

[gqshen <gq...@apache.org>]

Hi Sentry community:

   With Prasad's help , we have now officially branched Sentry 1.5.0.
This branch will keep consistent with Master branch. As indicated in
my previous email, we will complete the release process for Sentry
1.5.0 on

April 3th. Please help keep Master branch stable until release date so
we can have a smooth release. If you want to commit anything to the
1.5.0 branch, please let me know.  The following items were not
resolved, but  I want

to include these in the 1.5.0 release. If anyone is working on one of
these items, please resolve these before the release date.

SENTRY-500 : 1.4 to 1.5 upgrade needs to handle empty strings with __NULL__

SENTRY-670 : Fix the Sentry build to remove snapshot and non apache dependencies

SENTRY-676 : Address Sentry HA issues in secure cluster(Fix ZK Acl
resetting logic part)

Respectfully
Guoquan Shen