Move known CSS properties into data file

Including the list of properties in the class definition was a bit
unconventional. Move the property list into a separate file.

At the same time, update the list of properties using the data from
http://www.chromestatus.com/metrics/css/popularity (which was suggested
in #29).

This brings the property count from 256 up to 465 unique properties.

Closes #61, #65.

Change-Id: I916bf8db79c6f3c9eb7b2575c6b0f28caac4d5e2
Reviewed-on: https://gerrit.causes.com/32422
Tested-by: jenkins <jenkins@causes.com>
Reviewed-by: Shane da Silva <shane@causes.com>