y_axis needs a width to prevent large zone of white space to the left of the chart

Specify a width for y_axis to prevent large zone of white space to the left of the chart i.e. with this change chart is left justified on the page instead of quasi-centered.

Using Chrome 38.0.2125.101 on Ubuntu 14.04 the lack of a width results in a y_axis 350px wide. The Rickshaw generated y-axis is 29px wide so that's 321px of whitespace to the left of the y-axis.