added code coverage tracking

.travis.yml

@@ -6,4 +6,10 @@ php:
 
 before_script:
     - curl -s http://getcomposer.org/installer | php
-    - php composer.phar install --dev
+    - php composer.phar install --dev
+
+script: phpunit --coverage-clover clover
+
+after_success:
+    - curl -sL https://bit.ly/artifact-uploader | php
+