Drop sorted() from event_handler

This breaks on python 3 with "TypeError: unorderable types:"

The sorting was originally added to irclib to fix
https://sourceforge.net/p/python-irclib/bugs/9/
( in https://github.com/jaraco/irc/commit/ad159cbbf1d00fe15876a61d0abf88e43f5112ca)
but as irkerd doesn't have event priorties, the issue doesn't
apply here anyway.

This closes #11.