Re-order functions in module

This is for readability.

Signed-off-by: Zack Cerza <zack.cerza@inktank.com>
Add new ssh_keyscan() method

This is just a cleaner implementation that will replace the existing
one(s).

Signed-off-by: Zack Cerza <zack.cerza@inktank.com>
No need to be passing ctx to update_lock()

Signed-off-by: Zack Cerza <zack.cerza@inktank.com>
f or update_keys or scan_for_locks
f
Use new ssh_keyscan() function

Signed-off-by: Zack Cerza <zack.cerza@inktank.com>
Rewrite ssh public key updating

Signed-off-by: Zack Cerza <zack.cerza@inktank.com>