Create balance_tracker GUI

Create web UI that has an edit box where user can type name of account to graph. After some number of characters have been typed, dropdown should appear below edit box with possible account names that match partially typed name (dropdown filled using find_matching_accounts). Pressing enter or button beside the edit box (called "show balances") with a valid account name should call get_balance_for_coin twice (with hbd and with hive passed). These two tuples of (block_number, balance) should then be graphed for each coin.