For Travis CI - add CI build using Clang, optimize for MinGW install.
For Travis CI - only upload build artifacts from GCC compiler.
Exclude uploading build artifacts from Clang compiler for now as we have too many variants already.
Test [ci package].
Sync at 2014-10-03 21:27:41 +0800.

Conflicts:
	.travis.yml
	Source/CMake/Modules/Urho3D-CMake-common.cmake