move imports into factory functions
scrape committees and their IDs
MpCommittee.cdep_id column
update mp_committee table
remove views for committee membership
remove views about committee summaries
remove some committee-related tables
mp_committee.chamber_id
scrape all committees
extract committees from proposal activity
schema for policy domains
nullable=True is the default
proposal.policy_domain_id column
save policy domain for a proposal
calculate policy domains for all proposals
question.policy_domain_id column
classify questions by the policy domain
show policy_domain on proposal & question pages