"keybase push" lists disabled keys

Keys disabled through the "disable" command in GPG's edit-key shell still turn up in the keybase client's "push" key list.

I think it would be better to hide them. GPG after all pretends that disabled keys do not exist when attempting to encrypt for one too.

EDIT: For illustration purposes, my keychain contains keys that servers encrypt backups for. I disabled those keys so that I may decrypt the backups at any time, but the keys (despite being private keys) should never be used for signing or encryption on my end.

Start by reproducing the "keybase push" key list with a key disabled through GPG's edit-key shell. Trace how the client discovers keys for that list and verify that disabled keys are omitted while usable keys remain available; the issue does not name a source file or test.

Written by the indexing model from the issue text.