Suggestion to include a configuration setting to allow/disallow delegation on your node + whitelist wallets

[Istatkov]

Issue description

Currently anyone can delegate TRAC on the Mainnet (Gnosis) nodes. There is no controls over whether you would allow others to delegate on your node. This could lead to the following issues:

1. The delegators incurring losses from slashing and suing the node operator to cover losses.
2. Delegator with hacked funds delegating TRAC tokens to your node, where the node operator would become suspect of the creating the hack in the first place.
3. Node operator becoming liable for taxes on profits of the delegators because of unclear regulations.

Moreover some users would prefer to allow certain users to delegate on their node. As such the need for a whitelisting option would be ideal to be included, where the node operator can set specifically which wallets are allowed to delegate to the node.

Proposition

1. Include option "Allow Delegation (Yes/No)".
2. Include option list "Whitelisted wallets to delegate on the node": wallet 1, wallet 2, wallet 3, etc.

Benefits

This will allow users from areas with unclear laws and regulations to still be able to run a node they fulfil only with their stake, or have control over who can stake on the node.