Added ability to pass coverage api value and report type from client app config

[saloniy]

Added the ability to pass the value of the API from the client application instead of using write-coverage always as discussed. The default will be set to write-coverage just in case the value is not passed from the client app. Tested this with my app and it's working as expected after adding the coverageApiPath in my app's config/coverage.js

[krasnoukhov]

This looks useful to me