Bug Fixes & Minor Enhancements to 'dspace-replicate' version 3.x

All fixes / enhancements in this pull request have been tested thoroughly with 'dspace-replicate' version 3.x (with both METS and BagIt backends). 

## Bug Fixes
* Fix two NPE in processing object deletions in METS event consumer
* Fix NPE in both METS & BagIt event consumers when object deletion triggers MODIFY event
* Closed several input/output streams which were accidentally left open
* Ensured METSRestoreFromAIP cleans up its temp files
* Fixed CatalogPacker (which writes deletion catalogs) so that is supports BOTH "zip" and "tgz" formats ("tgz" packaging was not working properly)

## Minor Enhancements
* Ensured default settings in 'replicate.cfg' are DuraCloud compatible (DuraCloud doesn't allow for underscores in group names). Enhanced comments in this file as well.
* Enhanced results reports from RemoveAIP and BagItRestoreFromAIP
* Changed Deletion Catalogs (written by event consumers) to have a prefix of "DELETION-RECORD@" whenever 'packer.typeprefix=true' in replicate.cfg (which is the default setting).  This ensures deletion catalogs have a naming scheme of "DELETION-RECORD@[handle].[ext]" and can easily be identified.