Add claim (or similarly named) function to token contract to pay for RAM

[zlnvch]

You should be able to transfer the account row's RAM ownership to yourself. Alternatively, we can change the open function to set payer to yourself if it was already opened.

@arhag if you accept to add this function to the token contract, let me know what you want to call it and I can do the PR myself.

[arhag]

I like the idea of using the open action to take over ownership of RAM costs if ram_payer == owner.

[deckb]

Apologies I transferred to the wrong repo at first.