Bill relationships resolution improved

[jessemortenson]

I found a couple more problems with related bill resolution:

• Existing script was using too many DB queries and executed slowly, with lots of DB load (one query per unresolved relationship)
• Rows are being added to the related bills table that cannot be resolved, because the bill identifier being recorded (for the related bill) is not normalized. So it will never match the identifier of the related bill's record in the bills table.

So, I have made improvements:

• Uses the bill identifier normalization transformer in add_related_bill() so that we should no longer have un-normalized rows showing up
• The os-relationships command now by default checks for existing rows that have a common pattern of un-normalized bill identifier strings, and fixes them (which is a fair amount of DB querying, but should be a temporary measure)
• Improves the main part of os-relationships to query for all the candidates in a few queries, then match against a map of them, instead of query-per-unresolved-relation
• Adds support to filter by a particular session