CLI: Bug Fix + slightly easier configuration

When using 'sl config setup' you can now type in 'public', 'private',
or type your own endpoint URL.
Fixes a bug where if you don't have an API key it would fail to generate. Now
it should properly generate an API key for you if you don't have one when using
'sl config setup'
Merge pull request #132 from sudorandom/v3

CLI: Bug Fix + slightly easier configuration