Should still work with DIY gateways

[shawaj]

This container should still work for DIY gateways.

So we need to maintain ability to have file based key in persistent storage for that

This was removed in #25 / #27 but needs to be added back

[pritamghanghas]

@shawaj How do people with DIY gateways manage this file. Do they manually write it. Or they just use the default key. If so, how do they receive credits.

[shawaj]

@pritamghanghas if you check for it worked before you should see.

Basically as follows:

• if there is ECC use that
• if no ECC and no key file in persistent storage, create new key
• if no ECC key and there is a key file in persistent storage, then copy it into place

[shawaj]

https://github.com/NebraLtd/hm-gatewayrs/blob/ff53631945bfc5755f0113f36b78c96525397d70/start-gatewayrs.sh#L32-L46