LB-842: When a chained blog provider is deleted, the already selected blogs still appear on chained blog source

Fix OriginURI to be external url of the provider.
Merge pull request #258 from petrjasek/lb-842-source-origin-uri

Lb 842 source origin uri
Merge branch 'liveblog-15' into lb-842-hide-orphan-chained-blogs