Regenerate SSH keys

When using the image to install the SSH keys are the same for all installations.

This posses a huge security issue. I've added some lines to the installer to generate new keys on install.
This does not affect upgrades.
Nasty SSH fix

This will regen the SSH keys on each upgrade. As it's a good idea to periodically refresh keys, this isn't necessarily a bad thing.

Though this depends on how often releases are done.
Merge branch 'ssh-key-regen' of https://github.com/PartTimeLegend/minera into PartTimeLegend-ssh-key-regen
Regenerating on install but not on update
Merge branch 'PartTimeLegend-ssh-key-regen'