[libcloud] GoGrid's node password attirbute setting implemented

[Roman Bogorodskiy <bo...@gmail.com>]

Hello,

I've implemented setting password attribute for GoGrid nodes. It's a bit
hacky as GoGrid doesn't include password property in its
grid/server/list call, so I had to call support/password/list along with
server list call and fetch matching passwords from it.

I also added features = {"create_node": ["generates_password"]} to the
driver for deployment.

I've changed tests a little and did a manual testing of deployment and
it works for me.

You can pull this changes from my forked repo on github:

http://github.com/novel/libcloud

Feedback is welcome.

Roman Bogorodskiy