Priority change of already submitted WFs

[sunilUIET]

Is your feature request related to a problem? Please describe:
We come across situations where priority need to be changed after submitting WFs. For few WFs, we can do it manually in reqmgr page but it become problem when operation is required for a bulk of WFs.

Describe the solution you'd like:
Possibility of changing priority from rereco machine itself. For bulk operation, we should have some central script.