create js class for handling visualizations
pull out get_stats_data into it's own fn
add custom data parameter; add ability to override the url updating behavior; support week, month, and day intervals; fix global bug
allow users to set the interval
don't display graphs when the query returned no data
add ability to specify whether you're using hash-tabs; don't display the no-data text on load
fix stupid bug with no-data commit
Merge pull request #1074 from dimagi/viz

Visualizations Refactor