Enhancement: Enable caching of dependencies as installed with Composer

Author: localheinz

.travis.yml

@@ -5,6 +5,10 @@ sudo: false
 php:
   - 5.5
 
+cache:
+  directories:
+    - $HOME/.composer/cache
+
 env:
   global:
     secure: Yc+Xohkr/iEUU7FCQuSLXAE9ywNW9g6CfrM1Ki0Hl+fS15F3AXT7dFY8EyCJ4dP1/oI0dBmwrGWrltXV0XWIjGV1Ms3tefCgQpBBAqwT+hImzVP3RbpZW8Iyo2d0VgiDemQF1LWYD/pKu6d8WljTnv5D77NIMdEJjQ0uzeTLWdw=
@@ -13,7 +17,7 @@ before_install:
   - composer self-update
 
 install:
-  - composer install
+  - composer install --prefer-dist
 
 before_script:
   - git config --global user.email "travis-ci@codeclimate.com"