Add code for including one-shot update size in Manvr event

@aarvai - I have something for you to test.  I need to run, so the instructions are a bit brief, let me know if you have problems.

To test on GRETA:
```
ska-test-SOT@chimchim% ipython --pylab --classic

>>> import sys
>>> sys.path.insert(0, '/home/SOT/git/kadi')
>>> import os
>>> os.environ['KADI'] = '/home/SOT/git/kadi'
>>> from kadi import events
>>> mans = events.manvrs.filter('2014:001')
>>> mt = mans.table
>>> plot(mt['angle'], mt['one_shot'], '.')
[<matplotlib.lines.Line2D object at 0x5997890>]
```