Instead of broadening the patterns, this relies on realizing that almost all
query formats either won't match when a state name is present, or will work when
that name is replaced by the code.  So just preprocess the query string to
replace state names with their code before pattern matching.

Special case for vanity pattern ~ which can really be anything at all so don't
process that.

If you use it with a blank search it pulls from a fallback list for now.

Put them in the right place and also check from the InviteCodes handler

* child-signup:
  Refactor CutomerPlan to use value semantics
  Allow setting parent during signup using a special referral code

Lookup any referral code to see if it is one for setting a parent, if so set the
parent when we set the plan.  In the invite code flow, reload customer and check
balance and if there is enough then we can bill customer and proceed, no need to
add more credit or another code.

Verify parent when setting to make sure it has the same currency as the child
plan at creation time (note that updating the parent plan in the future can
violate this, so be very careful if/when we allow for that!)

* area_codes:
  When no results for a city, try area codes nearby

Array() converts dates apparently

If somehow we try to bill with no plan, give a better error

Creating it if it does not exist.