send an email as the notification

I prefer to get an email myself, so that's what I do first. I will
probably re-enable the jabber thing later again.

Idea: I could also make an IRC notifier, or HipChat, or ...
rename the whole thing to vervet-monkeys

A generic name like url-watcher was too boring; but watcher-in-the-water
was too long and really cumbersome to type.

Moved some methods and constants around as well.

I also moved bundler to the bin/ since I don't want to force bundler
upon the users of the library.