enable scrutinizer external code coverage

.scrutinizer.yml

@@ -0,0 +1,8 @@
+tools:
+    php_sim: true
+    php_pdepend: true
+    php_analyzer: true
+    external_code_coverage: true
+filter:
+    excluded_paths:
+        - 'tests/*'

.travis.yml

@@ -49,3 +49,5 @@ script:
 after_script:
  - cd $CURRENT_DIR
  - php vendor/bin/coveralls -v
+ - wget https://scrutinizer-ci.com/ocular.phar
+ - php ocular.phar code-coverage:upload --format=php-clover build/logs/clover.xml