Don't try to upload to QA Dashboard if not enabled

Previously cap deploy:setup did ask if user wanted to set up exporting
to QA Dashboard but didn't really follow the answer - upload was always
tried but since the token/url were incorrect it just didn't work. This
makes no sense so now we check for enabled flag in the file and just
return true if it has been set and is set to false.
Added Gerrit integration (no tests)

Previously QA Reports could link to Gerrit with the plain link approach.
Now it can fetch title and status for Gerrit items the same way as
Bugzilla is handled.
Fix Gerrit initializer and deploy script

- Check Gerrit uri and link_uri parameters
- Ask for Gerrit HTTP credentials upon deployment
Documentation updated
Fix incorrect whitespace