Simplify remote configuration, ssh key generation/configuration

[isc-tleavitt]

Following best practices for setting up deploy keys - it's a little challenging to get the remote configuration "just right" at the moment. I think this boils down to:

• Showing the public key in the settings UI
• (Perhaps) automatically generating a key pair for use as a deploy key (need to consider security ramifications of this first though)
• Supporting remote configuration through the main UI

[isc-tleavitt]

Re: security ramifications of simplifying this process, I'd want to consult with @mdmcl first.

[isc-tleavitt]

Also need to think about multiple repositories in the same namespace (e.g., in a package manager-aware context)