add merged scripts

[areinsvo]

Added new script, assign.py, which merges the functionality of assignWorkflow.py and assignProdTaskChain.py.

[prozober]

We need to change this line because the HTCondor collector is going to be migrated (https://hypernews.cern.ch/HyperNews/CMS/get/comp-ops/2929.html). It is better if we do some tests.

[areinsvo]

I changed the line Paola mentioned above, so that global_pool points to the landb alias 'cmsgwms-collector-global.cern.ch' for monitoring systems. I've tested it and it works as expected.

[vlimant]

Could you please go as far as using the siteInfo class in utils.py to get the list of sites in a more dynamic way ?
Can you please report below what are the tests that you have performed for this assign.

[vlimant]

please make --lfn mandatory.
we'll find a way to fetch the value from a relevant place in due time : i.e after merging this