MAYA-91350 - OSX builds for Pull Request in https://github.com/imagew…

…orks/OpenColorIO failed

Trying several thing in a fork and finally found that using pyenv as suggested in hvac/hvac#75 worked.
Validate that all builds are now passing on my fork.

.travis.yml

@@ -35,6 +35,10 @@ before_install:
   - if [[ "$TRAVIS_OS_NAME" == "osx" ]]; then
       brew update;
       brew install glew;
+      echo 'eval "$(pyenv init -)"' >> .bashrc;
+      source .bashrc;
+      pyenv install 3.5.2;
+      pyenv global 3.5.2;
     fi
 
 # Run the Build script