update to newer version

based on the plugin from @ask
Merge pull request #269 from Eleme/master

Update to a better rabbitmq munin plugin
fixed duplicate value when read/write values == 0
Merge pull request #270 from tsaavik/master

Fixed bug in zfs plugin: zpool_iostat
Merge pull request #268 from mhwest13/master

Memcached Multi Plugin Overhaul
Add plugin for monitoring Apple Airport devices via SNMP
Merge pull request #271 from cmsj/master

Add a plugin to monitor Apple Airport devices
time/ntp_packets: set minimums to zero to avoid spikes on counter restarts
Minor bugfixes