Update Travis to trusty and increase PHP memory limit

.travis.yml

@@ -1,6 +1,6 @@
 language: php
 
-dist: precise
+dist: trusty
 
 addons:
   firefox: "31.0"
@@ -28,6 +28,7 @@ before_script:
   # Init PHP
   - phpenv rehash
   - phpenv config-rm xdebug.ini
+  - echo 'memory_limit = 2G' >> ~/.phpenv/versions/$(phpenv version-name)/etc/conf.d/travis.ini
 
   # Install composer dependencies
   - composer validate