Remove unused import.
Move component loader to util module.
Restore backwards-compatibility in ranker(s) argument.
Implement voting between individual scoring functions.
Use appropriate Queue method.
Add default values to command line arguments.
Print error in usage.
Pad score appropriately.
Add filtering step, right after gathering.
merge, --ours on tweetRecommender/query.py
Add expected publishing time filter.
Strip down gathering step.  Use filtering; add projection.

It now only returns the MongoDB db.collection.find() criteria for
collection, so that we can hook our filters into the same call and also
add projection on fields.

This comes with a change to all scoring components as well, in which
they need to define the fields they are interested in.