McObot only reports parts on the staff channel, not joins

[Riot]

Resulting in some silly looking spam.

Whoever added the dodgy part notification should also fix the join notification.

[Riot]

That would be this commit: http://code.minecraftonline.com/scripts/commits/037a728d995a1c2248e3a2472b66639347991856

[14mRh4X0r]

Also announce staff channel joins, closes #176

→ <<cset 44cedbd319bc>>

[Riot]

Crashes on minecraftonlinestaff join now.

Traceback (most recent call last):
  File "./mcobot08.py", line 934, in <module>
    irc.run()
  File "/home/minecraft/ircbase.py", line 70, in run
    self.decide(event)
  File "/home/minecraft/ircbase.py", line 112, in decide
    self.on_join(sender, chan)
  File "./mcobot08.py", line 488, in on_join
    message = '% joined the staff channel.' % nick
ValueError: unsupported format character 'j' (0x6a) at index 2

Also apparently attempts to report itself joining the channel.

[Riot]

staff channel joins not crashing bot, resolves #176

→ <<cset 71d53cdb5860>>