Delrifai/#412 verify account starts with @

1. Validated that account starts with @ else show the error page
2. Validated if the account starts with @, it is also not empty, and there is a username after it
3. Performed Sanity check on balance history and main account page to make sure all is working as expected

Changes applied for balanceHistory/@bkocktrades(balance history) and @blocktrades (main account)