basic browserid support for web.py

browserid.py

import urllib, json
class FalseStorage(web.storage):
    def __nonzero__(self): return False

def browserid():
    c = web.cookies()
    if c.get('browserid_assertion'):
        out = urllib.urlencode(dict(audience=web.ctx.host, assertion=c.browserid_assertion))
        o = json.loads(urllib.urlopen('https://browserid.org/verify', out).read())
        if o['status'] == 'failure':
            return FalseStorage(o)
        else:
            return web.storage(o)
    else:
        return web.storage()