Adds Password Auth to CLI Configuration

This change introduces the ability for 'sl config setup' to be given your
username/password and it will go out and grab your API key or generate one if
one does not exist.

 * Moves format_output to SoftLayer.CLI.helpers
 * API Key/Password input is masked
 * The username/api key is displayed on screen before verifying.

Example Usage:

```
$ sl config setup
Username: someuser
API Key or Password:
Endpoint URL [https://api.softlayer.com/xmlrpc/v3/]:
:..............:..................................................................:
:         Name : Value                                                            :
:..............:..................................................................:
:     Username : someuser                                                         :
:      API Key : oyVmeipYQCNrjVS4rF9bHWV7D75S6pa1fghFl384v7mwRCbHTfuJ8qRORIqoVnha :
: Endpoint URL : https://api.softlayer.com/xmlrpc/v3/                             :
:..............:..................................................................:
Are you sure you want to write settings to "/Users/username/.softlayer"? [Y/n]: y
```

**Pending Question**: Is the verification necessary? It seems like an un-needed step at the moment since the credentials are already verified by the time you get asked if you want to save.