Make control loop more robust

[bbockelm]

The control loop does not handle errors well. We can make this more robust by:

1. Switch to python logging, allowing the admin to see the timestamp of a certain action.
2. Redirect stdout/stderr to append to files in the working directory. Otherwise, HTCondor always overwrites the stdout/stderr in the case of a crash.
3. Go through the control loop and catch / log known exceptions instead of causing the control loop to exit.