LB-521 : Incorrect live blog model url
LB-499: Add provider no action

Use xfilter for creating new providers so it gets
data needed for rendering.
LB-499: Add provider no action

Fix external blogs rendering when provider url is changed.
LB-499: Add provider no action

Fix subscribed blogs lookup.
LB-552: Manage Feeds - mess up with an incorrectly supplied provider URL

Add validation for provider name and url fields.
LB-550: When provider is deleted there is no sign blogs are unchained

Add confirmation on provider delete with info that blogs are unchained.
Merge pull request #42 from petrjasek/liveblog-13

lb-499 Manage Feeds -> Add Provider -> no action on submitting provider info
lb-550 When the provider is deleted the user is NOT informed that all chained blogs will be unchained.
lb-552 Manage Feeds -> mess up with an incorrectly supplied provider URL