Merge branch 'master' into working
Create Legend

Adds a legend to the chart, drawn from each series' name and colour.
Position of the legend is currently hardcoded to be the top-right(isn)
corner.

The sizing of the chart elements was being handled by the init() and
resizeChart(), the latter of which is called by draw(). Instead, all
resizing is now handled solely by resizeChart().

I also found that insight.Constants.Chart no longer exists, as it is now
the PlotArea, so i've fixed this up too.
Test the legend

Adds tests that the legend positions and sizes correctly, and extracts
the correct info from the series'.
Merge branch 'develop'

Conflicts:
	Gruntfile.js
	insight.js.zip
Addressing github comments

Most of the anonymous functions from the legend drawing have been moved
out to private variables, to avoid creating them each time we draw. The
one exception is the text width function, as this required the ctx var,
which we can't get at from a private variable otherwise.

Also moved the view logic for the legend into a legend.init() method,
and defaulted the chart to not having a legend, unless the chart.legend()
method is called.
Merge pull request #80 from tpkelly/master

Add legend to charts