Retrieve balances from MetaMask (non-logged-in user)

[dnaidionov]

Upon connection to MetaMask we should:

1. Get a list of addresses in the wallet
2. For each address go through the list of [ETH, CARD, popular tokens (as defined in https://github.com/MetaMask/eth-contract-metadata )] checking against our indices, not the network.
3. If ETH or token balance is non-zero, then we display a card for that network/address/token (Create Crypto Currency/Token balance component - embedded view #188)