Currency icons - ERC20s not on Coingecko

[jyap808]

I think this is looked up via an external API call with graphics hosted on an external service.

Related to issue #13

Hard code the icons and remove any API lookup.

[jyap808]

Looks to be resolved with c8d7129 for UBQ and GEO. Icons don't show up for others. Probably because they aren't on Coingecko. Need a workaround for this.