Support for resources, ask about action after login

Asking about action after login ensures, that the user can be
shown only parameters he is authorized to use.
Fix wrong module names in client
Authentication providers in client, supports basic and token auth
CLI: support authentication providers
Readme: update auth example
CLI: add option to save auth credentials to config file

Config file is located at ~/.haveapi-client.yml.
Cli#server_config: fix return value if server is not found
CLI: remember last used auth method, fix saving basic auth

Last used authentication method is used when no other is specified.
Token auth: save and check token validity, rerequest token if possible
README: update authentication info in CLI
Send Communicator#identity as User-Agent in every request
Client: allow changing identity via constructor argument
CLI output formatter: handle null resources
Change license to MIT
Version 0.2.0