Support Ohloh account names instead of just numbers

Since this module was released, Ohloh rolled out named aliases for account numbers. These are what now appear in one's Ohloh profile url, e.g., https://www.ohloh.net/accounts/turadg

For anyone who has an account name, finding the number can be quite difficult. This patch changes the terminology from "account number" to "account identifier" and removes the requirement that the input be a numeric.