Install pyenv via Homebrew on Mac

Author: BanzaiMan

.travis.yml

@@ -32,11 +32,17 @@ env:
     - ALIAS='nightly'
 
 install:
-- pushd /opt/pyenv/
-- sudo git checkout master
-- sudo git pull
-- popd
-- python -m pip install virtualenv
+- |
+  if [[ "$(uname)" == "Linux" ]] ; then
+    pushd /opt/pyenv/
+    sudo git checkout master
+    sudo git pull
+    popd
+  else
+    brew uninstall pyenv
+    brew install pyenv --HEAD
+  fi
+- sudo -H python -m pip install virtualenv --upgrade
 
 before_script:
 - 'export INSTALL_DEST=${INSTALL_DEST:-/opt/python}'