Making a bunch of warnings and an error go away.

Ruby 1.9.3 had a good point about "folderstyle = MBox" not actually
affecting anything on account of how I was setting a local variable
called that instead of the class member.

But really, that complaint about indentation being slightly off?  That's
excessively picky.
Merge branch 'master' of github.com:dagbrown/gurgitate-mail