Remove lowercasing of channel names in some places

When in a mixed-case channel like freenode #rapidSMS, the nick list was
not showing up. It appears to be due to inconsistently converting the
channel name to lower case, and rather than trying to lowercase it
everywhere, it seems simpler to just leave it alone.
Merge pull request #1 from poirier/mixed-case-channels

Remove lowercasing of channel names in some places