Memory request for cappadocicum

Hi Andrew. Over the last day or so I've received 21 notices about cappadocicum running out of memory...

Traceback (most recent call last):
  File "/srv/doctor.torproject.org/doctor/consensus_health_checker.py", line 636, in <module>
    util.send("Script Error", body_text = msg, destination = util.ERROR_ADDRESS)
  File "/srv/doctor.torproject.org/doctor/util.py", line 97, in send
    stderr = subprocess.PIPE,
  File "/usr/lib/python2.7/subprocess.py", line 679, in __init__
    errread, errwrite)
  File "/usr/lib/python2.7/subprocess.py", line 1153, in _execute_child
    self.pid = os.fork()
OSError: [Errno 12] Cannot allocate memory

Strange. This is indicating an OOM while sending email at the end, not for fetching the descriptors (which should be the memory intensive bit). Oh well...

We ran into memory issues before and you said that it's trivial to add more, but want to keep the virt as lean as possible. Mind adding more? Unfortunately the above stacktrace doesn't give me any hint about how much is necessary so I leave that to your judgment.