RD-1361 Queued executions: start executions from the same dep first (#2759)
RD-1361 Queued executions: start executions from the same dep first (#2759)

When dequeueing executions, run all the executions for the same
deployment as the one that just finished. Before system workflows
even.

For now this is uninteresting, but when we add groups into this
(in RD-1640) it'll be more fun.
cloudify-cosmo/cloudify-manager,cloudify-cosmo/cloudify-manager,cloudify-cosmo/cloudify-manager