Ensure that each crypto/token supports the correct decimal places

Need to check the protocol specification for every crytpocurrency and token supported by our wallet, to ensure that we support the correct number of decimals. Some use only integers, while other have anywhere between 1-18 digits past the decimal. For instance, Bitcoin uses 18 decimals, as does many ERC-20 tokens. In the future, there may be others that support greater than 18 decimals, so we need to be forward-thinking and prepared.