Bring the Apple class up to date some more.

 - NSApplication no longer exists in java on OS X.
 - Apple introduced requestUserAttention to Application, so use it there
 - Remove no-longer-required interface
 - Add new methods from Application
 - Tidy up the reflection a bit.

Unfortunately, looks like we still need the native library, as the
OpenURIHandler doesn't appear to work unless java is launched using
Apple's own JavaApplicationStub :/ (Which is another separate native binary
and means we lose the ability to update the client due to not using our
launcher.)

Change-Id: Ia69481b3de7889265ffd848aba8aa2bd51e9acf0
Reviewed-on: http://gerrit.dmdirc.com/2571
Reviewed-by: Chris Smith <chris@dmdirc.com>
Automatic-Compile: DMDirc Build Manager