adding cursor.description and cursor.fetchmany()

[WilliamStam]

i added a PR to patch this in #25 but incase somone lands up here and PR isnt accepted or delayed then a "sneaky" fix would be to do something like this:

 class Cursor():
        def __init__(self, baseObject):
            self.__class__ = type(baseObject.__class__.__name__,(self.__class__, baseObject.__class__),{})
            self.__dict__ = baseObject.__dict__

        @property
        def description(self):
            return self._cursor.description

        async def fetchmany(self, *args, **kwargs):
            return await self._loop.run_in_executor(self._thread_pool, self._cursor.fetchmany, *args, **kwargs)

and usage would be something like

conn = await self.connection.acquire()
self.cursor = Cursor(await conn.cursor())

(its less than ideal but hey... cowboy thursdays right!)

another issue for description: #19

[WilliamStam]

came across a use case that i need to set the outputtypehandler

this works

        def output_type_handler(cursor, name, default_type, size, precision, scale):
             ....

        oracle_pool = await cx_Oracle_async.create_pool(...)
        async with oracle_pool.acquire() as connection:
                async with connection.cursor() as cursor:
                    cursor._cursor.outputtypehandler = output_type_handler