change login form label to prefer emails
faster tooltips with x-line for larger graphs (similar to sparklines)
split tooltip methods into separate file
extra padding when on right
updated help to include info on zoom/pan
fix panning via touch events; don't allow panning along the y-axis
enable panning in fullscreen view
pinch-to-zoom can act like a pan sometimes (zoom out, near edge, etc)
large refactoring: created Graph class to contain all related code
handle a mouseup which occurs outside of the browser window
fix NPEs on dygraph
use new Graph class
created Sparkline class
fixed REST call for metrics by check