Web service support for custom container usage.

[tskluzac]

Add mechanism for fetching the user-registered containers from Joao's DB table. Then register the base_extractor as a function for all of them. Will likely need to make ALL of your changes near line 47 in configure_bp.py and line 38 in test_all_extractors.py:

https://github.com/xtracthub/xtract-service/blob/master/routes/configure_bp.py#L47

xtract-service/tests/extractors_at_compute_facilities/xtract_jetstream/test_all_extractors.py

Line 38 in a41a717

extractors = extractors_to_test.ALL_EXTRACTORS.keys()

Might need to add /home/ directory containing the .xtract/.containers directory to database that we plan to run functions on.