added urls_local
Added service/environment validation to relevant forms and extracted the
code that is common to them into a ServiceCatalogMixin.
Merge pull request #1149 from ar4s/improvments/local-urls

Local urls
Fix for the 'Manual device' form when both asset and model are missing.
Merge pull request #1151 from xor-xor/ralph_1955

Added service/environment validation and fix for missing asset.
Merge pull request #1152 from andrzej-jankowski/develop

[Scan] change detection fix
Syncing 'develop' branch.