Travis CI: site documentation update at 2014-03-25 21:58:25 UTC.

Commit: https://github.com/urho3d/Urho3D/commit/31ce69b490607017ce71829a15b100bab362ee73

Message: DrawableProxy2D operation fixes. Should fix crashes with worker threads and sprite flickering. Note that there is no frustum culling for Drawable2D's, as the vertex buffer for all of them is generated at once, and culling would be problematic for multiple views. Closes #252.