DBSession as default parameter

[ThomasJunk]

ringo/ringo/model/base.py

Line 899 in 510e7a7

def load(self, id, db=DBSession, cache="", uuid=False, field=None):

came with the last Pullrequest #90

Is not the common python pattern, but from my point of view without problems (DBSession is already treated like a "singleton").

@g-tom @toirl