Support for acl, networks, reporting, server farms, vips,...

Support for acl, networks, reporting, server farms, vips and some bugfixes

Quite a lot of additions (even if I say so myself).
It is now possible to go from nothing to functional vip by just using the gem.

The opsource API has a wicked sense of humour: when I got to server farms, they use standard POST parameters instead of XML parameters. Also had to adapt the headers here as the api would not accept "text/xml"

I also introduced a default password parameter in client, the gem takes this pw as the default when it is not specified in a server creation parameter.
I'm also thinking about introducing a similar "current_network" variable. That way, the network id doesn't have to be included in (almost) every request.

What do you think?