Remove cross platform CI

Author: karimnaaji

.travis/build.sh

@@ -11,6 +11,3 @@ machine:
 test:
   override:
     - /Applications/Unity/Unity.app/Contents/MacOS/Unity -batchmode -nographics -silent-crashes -logFile $(pwd)/unity.log -projectpath $(pwd) -buildOSXUniversalPlayer "$(pwd)/tangram-unity.app" -quit
-    - cat $(pwd)/unity.log
-    - mkdir NativePlugin/build
-    - cd NativePlugin/build && cmake .. && make