clear summary after it has been logged

Locally `grunt` did not work for me nearly all tests are red. I don't know why I hope it is working on travis :smile:. 
If you want me to add some tests, could you give me pointer where to add it and how to set the development environment. 

This pull request only resets the `summary` array after it has been run. Previously the summaries were kept and all consecutive runs would only add to the old summaries. This fixes #145.