added specular term
made spec its own light
syncing with master
syncing with master
sync with master
cleanup
Merge branch 'specular-dev' of https://github.com/meetar/tangram into meetar-specular-dev
small cleanup/tweak on specular light shader
add switch for specular light in lighting wrapper
add switch for specular light in demo
update build w/specular light
Merge branch 'meetar-specular-dev'