v7.0-beta.90

* Issue **#2087** : Fixed NPE caused during legacy migration.

* Uplift guice to v5.0.1.

* Issue **#1871** : Invalidate the users and user groups cache when the _manage_users_ command is run.

* Issue **#2064** : Delete empty directories left by running unit test.

* Add index to cluster_lock table to fix whole table locking for single lock key.

* Issue **#2059** : Add cluster lock protection to task creation. Stops duplicate task creation when master node changes.

* Change task creation by master node to try to wait for search tasks to complete and to try to only create the configured number of tasks.

* Refactor logic to determine master node into one place. Fixes discrepancies between UI and back-end.

* Change node monitoring screen to return nodes in name order.

* Issue **#2066** : Add data bars to node monitoring screen.

* Issue **#2059** : Fix `Duplicate key` error in task assignment.

* Issue **#2056** : Fix error sending permission change events to other cluster nodes.

* Add JVM OOM args to zip distribution scripts.

* Issue **#1866** : Change zip distribution shell scripts to execute from anywhere.