Added verify_ssl_cert and networkid options

verify_ssl_cert can be used to disabled SSL certificate verification, which
is useful in case a self-signed certificate is used on CloudStack server.
networkid can be used to launch the server into a specific network.
Also it uses extra['password'] that is provided by latest version of libcloud.

As a result, I get to have cloud.providers and cloud.profiles files like the following:
cloud.providers 
```
mycloud:
  apikey: "Some Key"
  secretkey: "Some Key"
  host: "cloud.ops.dot"
  path: "/client/api"
  provider: cloudstack
  verify_ssl_cert: false
```

cloud.profiles
```
small:
    provider: mycloud
    image: CentOS 6 minimal
    size: Small Instance
    location: YUL01
    ssh_interface: public
    keypair: mycloud
    networkid: ab815684-880b-4c45-91ce-8e8041d15e63
```