Lots of nice tracing.
Ignore vim undo files.
Add flag to enable / disable tracing.
Fix disable_tracing flag.

Can't evaluate at import time. Flags are only parsed in main() whereas import
happens before main() is called.
Don't disable security API if using NOOP firewall

nova assumes that quantum has a security group API. Using the NOOP firewall
breaks nova.
fast python implementation of dnsmasq callback

Serializes dnsmasq execution. Executed a few times per domain.
Significantly lower CPU utilization than original version. Not as fast
as the C version but better chance of getting upstreamed.