Removed spurious collectd reference

There's a old reference to the collectd module hanging around in
puppet-coe that isn't necessary any longer thanks to other changes.
It's presence there causes collectd to get installed even if
users remove it from the class group mapping.  This patch removes
the reference.

Thanks to dvorak (Clayton O'Neill) for finding and suggesting
the fix.

Closes-Bug: #1304179
Merge pull request #49 from CiscoSystems/bugs/1304179

Removed spurious collectd reference