Fix OSX releases

Author: ruslo

.travis.yml

@@ -40,7 +40,7 @@ script:
   - build.py --verbose --pack TGZ --config ${CONFIG} --toolchain ${TOOLCHAIN}
 
 before_deploy:
-  - gem install mime-types -v 2.6.2 # workaround for https://github.com/travis-ci/travis-ci/issues/5145
+  - rvm 1.9.3 do gem install mime-types -v 2.6.2 # workaround: https://github.com/travis-ci/travis-ci/issues/5145#issuecomment-158766310
   - export FILE_TO_UPLOAD=$(ls _builds/*/Foo-*.tar.gz)
 
 deploy: