Don't make the user choose whether they are using Fedora

[mjordan]

Instead, check whether $flysystem['fcrepo'] (or whatever) is set. Or, to check the files_managed table to see if there are any files that use the fedora:// URIs.

[mjordan]

Also, while grep -r use_drupal_urls * results in the expected results, grep -r use_fedora_urls * results in a single hit. WTF? This should be removed.

[mjordan]

One way of determining if fedora is being used is to query the file_managed table for uris starting with 'fedora://':

select count(*) from file_managed where uri like "fedora://%"

Maybe this could be run in the .install file to set the default for the "Use Fedora URLs" admin setting. That way, we can avoid excessive db queries and also let admins override that setting if they need to (but we should add a description to the widget to say they should not change the value unless they know what they're doing).