Add GStreamer to OS X builds

.travis.yml

@@ -25,6 +25,7 @@ matrix:
         - os: osx
           osx_image: xcode7
           env: SPEC=macx-clang CONFIG=installer SHADOW_BUILD_DIR=/tmp/build_macos_install
+          sudo: required
         - os: osx
           osx_image: xcode7
           env: SPEC=ios SHADOW_BUILD_DIR=/tmp/build_ios
@@ -103,6 +104,8 @@ install:
   - if [[ "${TRAVIS_OS_NAME}" = "osx" && "${SPEC}" != "ios" ]]; then
         wget https://s3-us-west-2.amazonaws.com/qgroundcontrol/dependencies/Qt5.5.1-mac-clang.tar.bz2 &&
         tar jxf Qt5.5.1-mac-clang.tar.bz2 -C /tmp &&
+        wget https://s3-us-west-2.amazonaws.com/qgroundcontrol/dependencies/osx-gstreamer.tar.bz2 &&
+        sudo tar jxf osx-gstreamer.tar.bz2 -C /Library/Frameworks &&
         export QT_DIR=Qt5.5-mac-clang/5.5/clang_64 &&
         export PATH=/tmp/$QT_DIR/bin:$PATH &&
         export QT_QPA_PLATFORM_PLUGIN_PATH=/tmp/$QT_DIR/plugins &&