Warning notification for missing document in database

[garrensmith]

A document that does not exist in a database that does exist:
We display an error message, and then do a redirect to the _all_docs of the existing database.

A document that does not exist in a database that does not exist:
We display an error message that the database does not exist, there is a redirect to the non-existent database's _all_docs page, where the secondary nav and doc-jump component fail to load, but the document list can be populated with documents from previously loaded databases.

If a user attempts to access anything in a document (including design documents) that doesn't exist:
Redirect to the _all_docs view for the database, and throw and error of "The <doc_name> document does not exist."