Re-use the Mono install script from CppSharp in Travis CI.

.travis.yml

@@ -15,13 +15,7 @@ addons:
     - g++-4.8
 
 install:
-  - if [ "$TRAVIS_OS_NAME" = "linux" ]; then sudo apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv-keys 3FA7E0328081BFF6A14DA29AA6A19B38D3D831EF; fi
-  - if [ "$TRAVIS_OS_NAME" = "linux" ]; then echo "deb http://download.mono-project.com/repo/debian wheezy main" | sudo tee /etc/apt/sources.list.d/mono-xamarin.list; fi
-  - if [ "$TRAVIS_OS_NAME" = "linux" ]; then sudo apt-get update -qq; fi
-  - if [ "$TRAVIS_OS_NAME" = "linux" ]; then sudo apt-get install -y mono-devel; fi
-  - if [ "$TRAVIS_OS_NAME" = "osx" ]; then brew install wget xz; fi
-  - if [ "$TRAVIS_OS_NAME" = "osx" ]; then wget -O mono.pkg http://download.mono-project.com/archive/nightly/macos-10-universal/MonoFramework-MDK-4.7.0.215.macos10.xamarin.universal.pkg; fi
-  - if [ "$TRAVIS_OS_NAME" = "osx" ]; then sudo installer -pkg "mono.pkg" -target /; fi
+  - external/CppSharp/build/InstallMono.sh
   - if [ "$TRAVIS_OS_NAME" = "linux" ] && [ "$CXX" = "g++" ]; then export CXX="g++-4.8" CC="gcc-4.8"; fi
 
 script: |