Fix travis mac build

Attempt to fix mac build of travis in respect to:
- Could not install packages due to an EnvironmentError: [Errno 13] Permission denied: '/usr/local/man'

.travis.yml

@@ -29,6 +29,7 @@ jobs:
 
 before_script:
     - if [ "${TRAVIS_OS_NAME}" == "osx" ]; then
+        mkdir -p /usr/local/man
         pip install --quiet conan;
         export HOMEBREW_NO_AUTO_UPDATE=1;
         brew install ghostscript;