On fresh cached files no UID lock was applied.

As revealed by debugging: with empty cache, a content
request that made Nx go remote, fetch, cache and serve
the content, the StorageFileItemRepresentation got a
file item which ContentLocator was not wrapped with
ReadLockingContentLocator (but it was plain FileContentLocator).

This means, that files served up like these (or processed internally)
were prone to deletion by some other thread, like request
for deletion of a parent directory or such.
NEXUS-5849: Fix
NEXUS-5849: Sharing the blacklist check

Pulled up the method call to check for remote server.
NEXUS-5849: Improving message
NEXUS-5849: OMG, Friday afternoon
Merge pull request #105 from sonatype/no-locking-on-freshly-cached-files

On fresh cached files no UID lock was applied.
Merge remote-tracking branch 'origin/master' into nexus-5849-artifactory-autorouting
NEXUS-5849: Mock was incomplete causing NPE
NEXUS-5849: Test adapted

Essence is same, "connection was refused", but this time it's detected before
nexus transport is consulted (transport error), instead the usual
java ioex message is sent, "connection to XXXX refused".

Assertion adapted accordingly.
NEXUS-5849: improvement for better message handling

The method checking for blacklist is throwing now
exception if needed.
Removed comments
Merge pull request #107 from sonatype/nexus-5849-artifactory-autorouting

NEXUS-5849: Central prefix file is served through Artifactory, which results in non-central artifacts being blocked
Merge remote-tracking branch 'origin/master' into nexus-5790-new-content-impl