Added USGS to the data collection.
Added shell script to setup.py
Added usgs instant and daily values.
Abstracted the USGS code
Modified setup.py to install text scripts.
Made a few tweaks to the IO.
Added filters to site meta IO for USGS.
pep8
update copyright
mark acis.StationDataIO as nested
WebserviceLoader base class; update ACIS classes
update CoCoRaHS and Hydromet classes
update acis scripts; store values in instance var
make filter_options computable as a class method
more robust handling of multi values
nested IO for multi-station data loading
support for state and county filters
custom user-agent string
merge from master
generalize default_params option