pyenv install (#713)
```
Unfortunately, since our latest image update, Python 3.5 doesn't come pre-installed anymore. Hence, you will have to install it via `pyenv` as a first step e.g.
before_install
- pyenv install 3.5.0 && pyenv global 3.5.0
support@travis-ci.com
```
diff --git a/.travis.yml b/.travis.yml
index 028e91a..b218c02 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -6,7 +6,7 @@
# http://stackoverflow.com/questions/22111549/travis-ci-with-clang-3-4-and-c11/30925448#30925448
# to allow C++11, though we are not yet building with -std=c++11
-before_install: pyenv global 3.5
+before_install: pyenv install 3.5.4 && pyenv global 3.5.4
install:
- if [[ $TRAVIS_OS_NAME == osx ]]; then
brew update;