only check perms if someone is actually trying to add or remove a factoid.
added the timez plugin
make timez a ChatCommandPlugin/Command plugin
Merge pull request #33 from uberj/timez-plugin

Timez plugin (and factoid permissions)
Added a persistent seen plugin

Fixes #30 except for the xseen part, which I don't think we should implement due to privacy concerns.
fixed up help.
Remove asserts and removed comment in queryUser.

I left queryUser() where it is because it works and getting the session is easier when its an instance method
allow excluded urls to be defined in the config file