[Crash-catcher] Catcut plugin

Denys, thank you very much for the Catcut plugin. I finally got a chance to look at it, and do some simple testing. It looks pretty good. I've filled out the add_attachment code in a patch below. I would appreciated it if you would review it, and check it in if it's acceptable. In writing this code I have come to believe that all of the plugins would benefit from having common bits of code factored out into a plugin support library, rather than cut and pasted from one plugin to another. I'm curious what other ABRT developers think of this. Also in looking at several plugins, I've noticed that different plugins have different policies for reporting errors, warnings, informational, and debugging messages. Sometimes exceptions are used, sometimes calls to 'update_client' and sometimes calls to 'log'. Is there a pattern/policy that I just haven't figured out yet, or is this still in flux? Thanks again. -gavin...