Note As of Winter '18 release, API v41, dynamic icons can be used with the native lightning:dynamicIcon component.
This includes two lightning components: svg and dynamic icon.
Dynamic icons stores the definitions contained on the Lightning Design System's Dyanmic Icon page.
The SVG component allows for you to render any svgs dynamically by supplying a json formatted string.
To view the sample dynamic icons in action, install the package and go to https://[your-instance-name-here].lightning.force.com/c/svgMockApp.app.