RFC: Add requirement for issuerFirm to be registered to allow use of setKYCApproval()

[Ryanmtate]

Problem:
There is currently no check if an issuerFirm is registered to be able to use the setKYCApproval method.

Adding this check would require an initial firm to be registered to allow addition of following firms.

At a low-level, a firm can be registered directly with the Storage contract by an owner of the storage contract.

Solutions:

• Add a modifier to check registration for issuerFirm
• Add constructor logic;
• Handle this at the tsm API level;

Possible solution is to add a method in the constructor of the TokenIOAuthority contract to set the default issuerFirm (i.e. Token, Inc.)

Code:

https://github.com/tokenio/tokeninc-smart-contracts/blob/45eff8892efb222ba9b21af099f09fea32e044b0/contracts/TokenIOLib.sol#L227

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As a reminder, issuerFirm is synonymous with a "provider". Providers are allowed to hold custodian funds and issue/destroy tokens at time of deposit/withdraw.