allow logger arg to MongoCache ctor. use logger objects rather than
logging.foo for any logging in caching.py
log the determined TTL value for caching facility in slicer controller.
beefed up wildcards considerably, supporting weeks, months, quarters,
years, hours in regex; specify python-dateutil requirement to use
relativedelta.
selecting hour unit will add hour to cut
added cubes_search optional requirement; bugfixes for cubes core
add cubes_search code and requirements; there's no need for a separate
module.
attributes are more carefully sourced for /facts endpoint in sql
mongo2 mapper supports set_locale with noop
got unit tests closer to passing for all sqsp code changes