0.19.6: zip / tar.gz / issues

Release Notes:

Upgrade Notes:

• Upgrading from 0.18 requires issuing a full flush of all the indices in the cluster (curl host:9200/_flush) before shutting down the cluster, with no indexing operations happening after the flush.
• The local gateway state structure has changed, a backup of the state files is created when upgrading, they can then be used to downgrade back to 0.18. Don’t downgrade without using them.

Bug fixes:

• elasticsearch fails to start due to verification error (#2051)