[storm] Meta data

[Gerdus van Zyl]

Hi,

I would like to propose the following small change to the Variable class:
def __init__(self, value=Undef, value_factory=Undef, from_db=False,
                 allow_none=True, column=None, event=None,**otherkwargs):

.....
        self._extrakwargs = otherkwargs

This allows arbitrary keyword arguments like:
creditlimit = Decimal(precision=(12,2))
that can be accessed using:
p = (one of self._storm_columns)
p._variable_kwargs['precision']

This is ultra handy for associating meta data specific to a database column.
Currently Variable is throwing a hissy fit (exception) when you try to do this.

Thank you.
Gerdus van Zyl