Track accounts using wildcards

I'd like to run a full node, with full account history, but only for a selected number of accounts (hundreds). Using the `--track-account` option is not feasible because the accounts to track will constantly change (new users added). Restarting the full node with a new list of accounts to track is a bad solution. As far as I know its not possible to change the full node config during run-time either.

I suggest that the config parameter --track-accounts will support wildcards so the following can be specified instead: `--track-accounts=myusers-*,myotherusers-*,*identifier*`

Alternative solution could also work, but is less flexible in my opinion:
https://github.com/bitshares/bitshares-core/issues/258#issuecomment-293612792

Start by tracing the full node's --track-accounts configuration and account-tracking entry points. Determine how wildcard patterns and newly added matching accounts would be handled without a restart; done means the documented wildcard examples work while preserving existing explicit account tracking.

Written by the indexing model from the issue text.