A couple bugfixes in Backendmerge

Hey Shawn, 

I'm back from velocity and getting ready to look at implementing the numbers-based backend stuff we discussed.  Before I start on that, I just wanted to PR a few fixes that make the version I just merged in from you run. 

I'm also fixing a bug I've been running into in process_log() where I get malformed input from Nagios every once in a while. I'm just wrapping the parsing code in a try block so that if I get bad input from Nagios, we log it and move on.  Here's an example of the log entry I'm generating from malformed output from a ping command: 

September 22 15:42:51 graphios.py CRITICAL failed to parse metric: -6] [-t <timeout>] [-r <remote version>] [-p <port>] <host>