0.17.8: zip / tar.gz / issues

Release Notes:

Enhancements:

• Support external versioning for deletes arriving before initial update (#1351)
• No need to reroute (check for possible shard allocations) when a new non data node is added to the cluster (#1368)

Bug fixes:

• Put mapping on a single node with new mapping will not wait for the mapping to be applied (#1355)
• Malformed REST create index causes the index to still be created (#1359)
• Fetch phase when searching might fail when mapping are updated with type missing (#1369)