Cache dependencies

.travis.yml

 os: osx
+env:
+  - PYENV_PYTHON_VERSION=3.5.0
 before_install:
   # Install and configure pyenv
   - ci/travis/before_install.sh
 
 install:
+  - pyenv activate sakia-env
   - pip install coveralls cx_Freeze
   - pip install -r requirements.txt
   - python gen_resources.py
@@ -16,3 +19,7 @@ script:
 after_success:
   - coverage -rm
   - coveralls
+
+cache:
+  directories:
+    - $HOME/.pyenv
\ No newline at end of file

ci/travis/before_install.sh

@@ -9,9 +9,11 @@ brew install pyenv-virtualenv
 eval "$(pyenv init -)"
 eval "$(pyenv virtualenv-init -)"
 
-env PYTHON_CONFIGURE_OPTS="--enable-framework" pyenv install 3.5.0
+pyenv activate sakia-env
+if [ ] then
+    env PYTHON_CONFIGURE_OPTS="--enable-framework" pyenv install $PYENV_PYTHON_VERSION
 
-pyenv shell 3.5.0
+    pyenv shell $PYENV_PYTHON_VERSION
     pyenv virtualenv sakia-env
 
     cd $HOME
@@ -35,3 +37,4 @@ make && make install
     pyenv rehash
 
     cd $HOME/sakia
+fi
\ No newline at end of file