Fixed the device image in the devices list (now shows image)
Merge pull request #296 from laf/issue-laf-40

Fixed the device image in the devices list (now shows image)
Start on graphing performance metrics
Poller run time graphing
Updated graph from area to line
Added ping response graphs and some small updates
Updated ping rrd response to include fping6 response
Added sql schema update for ping graphs
Fixed some scrutinizer warnings