Monitor ucarp processes.

On network and swift nodes, install a check which ensures
a ucarp process is running for each ucarp-vip present
in /etc/network/interfaces.

If no ucarp-vips are present, the check should never fail.
Merge pull request #374 from blueboxgroup/ucarp-proc-check

Monitor ucarp processes.
occurrences is used by sensu_check
Merge pull request #375 from blueboxgroup/failover-check-fix

occurrences is used by sensu_check