install a more modern pypy version

.travis.yml

@@ -12,8 +12,22 @@ python:
   - 'pypy'
 
 install:
+  - |
+      if [ "$TRAVIS_PYTHON_VERSION" = "pypy" ]; then
+        export PYENV_ROOT="$HOME/.pyenv"
+        if [ -f "$PYENV_ROOT/bin/pyenv" ]; then
+          pushd "$PYENV_ROOT" && git pull && popd
+        else
+          rm -rf "$PYENV_ROOT" && git clone --depth 1 https://github.com/yyuu/pyenv.git "$PYENV_ROOT"
+        fi
+        export PYPY_VERSION="5.0.1"
+        "$PYENV_ROOT/bin/pyenv" install --skip-existing "pypy-$PYPY_VERSION"
+        virtualenv --python="$PYENV_ROOT/versions/pypy-$PYPY_VERSION/bin/python" "$HOME/virtualenvs/pypy-$PYPY_VERSION"
+        source "$HOME/virtualenvs/pypy-$PYPY_VERSION/bin/activate"
+      fi
   - pip install -e .
 
+
 before_script:
   - if [[ $TRAVIS_PYTHON_VERSION == '2.6' ]]; then pip install --download-cache $HOME/.pip-cache unittest2; fi
   - if [[ $TRAVIS_PYTHON_VERSION == '2.7' ]]; then pip install --download-cache $HOME/.pip-cache coverage; fi;