ElasticGrid - improve life cycle of processing units
In elasticgrid, failure to deploy a PU can result in a "limbo" where this failure is not visible in ops-ui. Also in this state it's impossible to undeploy the PU through the ops-ui.
Improvement is to display the PU in ops ui before any nomad job is triggered. If the nomad job fails, it will be possible to undeploy the PU.