A reusable directive with customizable outer radius, inner radius,
label, and legend. Chart is updated on data change. Setting inner
radius to '0' will result in pie chart. Hovering over a slice will
show a tooltip.
This directive can be used to render quota charts in "Launch Instance"
workflow and related details panels.
Example Usage:
<pie-chart chart-data='instances'
chart-settings='settings'></pie-chart>
Partially Implements: blueprint launch-instance-redesign
Change-Id: I24f1e94b68c87617177806cbfe4542876b0eec47
23f45b7df1