Change decorators (http and fs)

Now decorators patch only request object. This allows us to interpret
the result of a request from a cocaine-runtime as an object with any set
of properties.

For example, now http-request has properties: body, meta,
request:

@http
def some_http_event_handler(request, response):
    """ curl -v "http://somehost.ru/some/handle/?a=1&b=2 """"
    req = request.read()
    body = req.body # Body - empty in example

    meta = req.meta
    method = meta['method']  # GET

    request_params = req.request # { "a" : "1", "b" : "2" }

PS. Full description of "meta" see in cocaine/decorators/http.py