Diff-cover

* Add support for specifying an external css file (thanks mgedmin)
* Add ESLint driver (thanks agroszer)
* Significant reworking of diff-quality to simplify the addition of drivers and potentially
allow a plugin system down the line. Something I would like to finish at some point but honestly I am just not seeing the time opening up in the short term. If anyone reading this wants to give it a go +1 to that.

Special thanks to Ben Patterson for taking some time to add some QA resources to this release

* Fix for windows users trying to run app (thanks evanunderscore)
* Fix handing source paths that contain spaces (thanks backupproject for pointing out the bug)

* Drop lazy to fully support python 3.5 (Thanks dashea for pointing out the issue)

* fix diff-cover when color.ui=always is set on git thanks Dundee

* Fix diff-quality when installed under a folder containing 'diff-cover' (Thanks faulkner)

* Fix handling of windows paths in cobertura files. Thanks to evanunderscore for catching and reviewing this bug
catching several flaws in my attempts to deal with this :-D