Rescope stroke style attribute on y-axis

In mbostock/d3 issue #1016, the scope of the `tick` class on a svg y-axis
element changed to include the entire g object (line and text), not just the
line. The Rickshaw CSS for `.y_ticks .tick` was created in the early commits, and
sets the style to be a 2px width semitransparent stroke.

Due to the change in scoping of the style class, the stroke element applies to
both the line and the text element, creating a shadow on the y-axis text labels.

By changing the scope of the stroke stanza from `.y_ticks .tick` to `.y_ticks
.tick line`, the stroke now applies only to the line, and not to the text
element, this removing the stroke shadow on the text label.
make new consolidate css file from src change
Merge branch 'yaxis-stroke'