Istanbul Clover report output

For this pull request, we have implemented a Clover reporter that is compatible with Atlassian Bamboo Continuous Integration server. Bamboo CI only accepts NCover or Clover format metrics, and this posed as an issue in our workflow. Others have also encountered the same issue documented here:

https://groups.google.com/forum/#!topic/karma-users/yww1YRdMi_s

I used a sample clover.xml output file as reference and implemented the clover.js file, which is a cloned and modified version of the cobertura.js file. The output format is tailored for Bamboo to capture all the necessary metrics for proper code coverage integration. It has solved an issue in our workflow and I believe this will be beneficial to anyone else who uses Karma and Bamboo CI.

I did not get a chance to create unit tests for our changes, as I ran into trouble running ‘npm test’ in the root directory and did not succeed. For now I just want to share this implementation to the public, but I would be glad to cooperate to get that done.