Travis CI: site documentation update at 2014-03-06 14:00:33 UTC.

Commit: https://github.com/urho3d/Urho3D/commit/7ae747063fba05141dc2dda109b57edf755ec498

Message: Rename "Unit Per Pixel" attribute in Drawable2D to "Pixels Per Unit" to match the actual behavior in StaticSprite2D / AnimatedSprite2D. Remove the attribute from ParticleEmitter2D class as it doesn't have effect. Closes #230.