Updated the ZeroFilled class to only fill when necessary

The new ZeroFill time series class created a lot of data points, which caused flot to perform poorly and wasn't really necessary. This modification will only place zero's before/after measurements when there isn't another measurement there. This ensures that the lines drawn by flot are accurate.

This also sets the line width on the bars to 0, so that 0 measurements won't show up on bar charts.