Travis: run tests also under PHP 5.6 and PHP 7.0 (firebase#108)

Author: petrkotek

.travis.yml

@@ -4,6 +4,8 @@ php:
   - 5.3
   - 5.4
   - 5.5
+  - 5.6
+  - 7.0
   - hhvm
 
 sudo: false