LDEV-2829 updating Apache Commons IO lib(This is done because "recent versions of FileUtils (such as the 2.0.1 release) have added the use of NIO for copying files; NIO can significantly increase file-copying performance, in a large part because the NIO routines defer copying directly to the OS/filesystem rather than handle it by reading and writing bytes through the Java layer.")
LDEV-2826: Allow marking Wiki pages as removed instead of removing them completely.Clear references to unexisting pages.Fix refresh Wiki page list after removing one.
