Adjust transaction fees based on if a transaction is a claim or not

[kaykurokawa]

Right now, transactions cost the same whether they contain a claim or not. Since transactions that contains claims take up more computing resources , we should adjust the transaction fees higher to reflect this.

[tzarebczan]

When determining a fee for claim transactions, we should take applications like spee.ch into consideration since the service owner (us in this case) pays for users' publishing fees. If we make them too high, the ability to run such services at no/little cost will be difficult.

[kaykurokawa]

Fixed with #95