Updated mediawiki/extensions
Project: mediawiki/extensions/Wikibase  04d0fa20ea86e8a04a91c3d8623602c2ecfa9c25

Clean up ExceptionHandler and MessageReporter

Moved to a better namespace,
put each class into a separate file,
added tests.

This also adds the (trivial) LoggingExceptionHandler.

Change-Id: I8a05d070572d86583929a0796e86a71f2157609e