Send ID and Text for preselected metrics to select2 modal
Only use proper numbers to calculate min and max

Math.min([..,null,..]) always = 0
Math.min([..,NaN,..]) always = undefined
(formatting only)
Ensure number formatting is always sent a number, not a string

formattedYValue can be a string, which causes a String.toFixed call, which is
invalid, later in Rickshaw
git issue? this was valid html, but something broke and then it wasn't.
Use more solid legend for stacked. prevents redraw shaky-cam action
bump version