Operations Center Server Plugin 1.5.4

Release can be confused with Disconnect, especially as there is no Disconnect action visible from JOC. Reworded the release screen to make it more obvious that it deregisters the client controller from the cluster. Added a disconnect screen

When provisioning nodes, return an accurate estimate for the number of executors that will be provisioned rather than returning the number of executors requested. Fixes issues with slow provisioning during spikes in the build queue length

None