Removes 5.2 and adds composer install directive

Author: Eoghan O'Brien

.travis.yml

@@ -1,7 +1,6 @@
 language: php
 
 php:
-  - 5.2
   - 5.3
   - 5.4
   - 5.5
@@ -13,6 +12,9 @@ cache:
     - $HOME/.composer/cache
     - vendor
 
+install:
+  - composer install
+
 script:
   - composer run-script test-build
   - wget https://scrutinizer-ci.com/ocular.phar