Add custom ExecutionTimeTestListener

Enables to listen to long running test. The phpunit xml supports the following settings:

- First argument enables/disables the listener
- Second argument specifies the threshold in seconds as the when the listener
should report a test.
```
<listeners>
<listener ...>
   <arguments>
      <boolean>true</boolean>
      <integer>10</integer>
   </arguments>
</listener>
</listeners>
```