In case of exceptions, Airsonic logs the full URL that triggered it
since 417583cc, including possibly sensitive query parameters such as
the authentication password/tokens passed to the Subsonic API.
This replaces the value set for this parameter in the URL by the
"<hidden>" string.
When Tomcat is not available (for example, when using Jetty), the
ClientAbortException is not available either, causing an error when
starting the server.
This commit fixes that, and instead catches that exception (or its Jetty
equivalent) via reflection.
The `ClientAbortException` exception indicates that the connection was
closed by the client, usually for something the server can do nothing
about (e.g. navigating outside of the page while it's loading).
Since this error happens often, this commit displays shorter error
messages when it does, without a large stack trace.
All other exceptions are handled just as before.
François-Xavier Thomas
Andrew DeMaria