Remove catch as comment module maintainer

It was a nice idea to try to find maintainers for all the different core modules in D7, but I am not remotely maintaining comment module - and it was an equally good idea to remove maintainers of systems when they had moved on.

Also, I thought I only agreed to maintain comment module if Moshe would too, but he's not in there, so either I got confused or some kind of trickery happened ;)

I'm still listed for 'Entity', 'Path' and 'Taxonomy', not sure path and taxonomy are going to get a lot of attention from me in D8 but won't kill those off just yet.