CB-7978 Fixed launching chrome in Linux

- Fixed launching chrome in linux. It either launches chrome or google-chrome processes
- Reads config.xml looking for the source file to be used at the lauching of the browser. This will work for Linux, Windows and MacOs
Actually, I'm not sure at all why you spawn & unref `google-chrome` but not `chrome`.  Is this intentional?  Do they run differently somehow?

Also a comment about the fallback to `google-chrome` if `chrome` fails to launch would be useful.