Add task for generating SVG Icon Fonts

These changes pull in gulp-iconfont to generate SVG Icon Fonts and gulp-consolidate to render a sass partial with the @font-face declaration and classes for your icons.

In this implementation, the classnames of each icon are set to `-#{filename}`.

How this gets used on a real project would vary.
This made sense to me because the icons task regenerates a sass partial which makes it a dependency of the sass task.