implement coveralls.io integration

.travis.yml

@@ -1,6 +1,15 @@
 language: php
 
 php:
-  - 5.3
   - 5.4
+  - 5.3
 
+before_script:
+  - composer require satooshi/php-coveralls:dev-master
+  - mkdir -p build/logs
+
+script:
+  - phpunit --coverage-clover build/logs/clover.xml
+
+after_script:
+  - php vendor/bin/coveralls