Server should automatically add a newly generated secret key to its keyring

[thomastaylor312]

When you start a bindle-server without a predefined secret key, it will automatically create one for you. However, it does not add this key to its keyring. It should do this automatically for 2 reasons: First is devex. Purposefully, a locally run bindle server and client share the same keyring for validation. If we don't auto add it, then we end up making the user do it. Second is that a bindle server should always have its own public key in its keyring anyway since we already trust it.

[thomastaylor312]

I plan on adding this before we cut 0.9 as it is an important devex change