move toilets icon to SVG

Implements part of #1165 by changing the icon for `amenity=toilets` to SVG (as requested by @mkoniecz in #1012). 

Symbol ([toilets-16.svg](https://github.com/nebulon42/osmic/blob/master/amenity/toilets-16.svg))
![toilets-16](https://cloud.githubusercontent.com/assets/3531092/5554255/eb8e4c46-8c49-11e4-9309-87807fa9bedc.png)

http://www.openstreetmap.org/#map=19/46.79772/13.49504
before:
![toilets_before](https://cloud.githubusercontent.com/assets/3531092/5554266/40fcc766-8c4a-11e4-93d6-6ec4be73eb24.png)

after:
![toilets_after](https://cloud.githubusercontent.com/assets/3531092/5554267/4675d0c0-8c4a-11e4-8cc1-48abe3f6ffe6.png)

A very similar symbol is also used by the HOT style, it is heavily inspired by Maki's [toilets-18.svg](https://github.com/mapbox/maki/blob/mb-pages/src/toilets-18.svg).