aggregator.py: add option to process triggers, add check to ensure only one schema is passed if triggers are aggregated

API overhaul

See merge request !27

add 'scald aggregate' as general purpose aggregator, move aggregator funcs to io.core, use utils.gps_now() for getting current gps time

influx.py: modify Consumer.query() to point to schemas for more intuitive usage, add Consumer.load() to load schemas from config. serve.py: fix typo causing issues with historical queries

UI overhaul

See merge request !26