Travis CI: site documentation update at 2014-10-15 09:31:11 UTC.

Commit: https://github.com/urho3d/Urho3D/commit/141c36aa77bac592943e2de25244a71f400f8fb6

Message: For Travis CI - add a rule to decide whether to skip universal build.
The threshold is currently set to 20 minutes (can be adjusted). If by the given threshold time the iOS build has not reached the checkpoint then the universal binary build is skipped automatically.