Add dashboards for SORN and tax-disc
Fix stub controller config and syntax in stub response

@jcbashdown, @gtrogers
Add dashboards for sorn and tax-disc
@wip Remove failures and availability from overview page, cucumber failing
Update feature tests for vehicle licensing dashboards
Rename many things from excise duty to licensing
Rename external references to vehicle-excise-duty
Merge pull request #162 from alphagov/sorn-and-tax-disc-dashboards

Sorn and tax disc dashboards