Reverting on-hold action

[paorozo]

If an "on-hold" action is taken over a workflow, we need to be able of put it back to "manual-assistance", in order to take another action. @dabercro @areinsvo @vlimant

[vlimant]

please don't use the functionality from the wtc-console until we solve this

[vlimant]

@sharad1126 setting "hold" from the console can resume, once #364 is merged

[sharad1126]

I think we should merge it.