use correct account status path if the tld is .us, add param for vers…

…ion in Client.get_account_status

The paths for the .com and .us account status endpoints have diverged. We now check the tld configured in the Client and use path 'accountStatus' if the tld is .us. We also allow the caller to pass an api version, which defaults to 1 if not passed. This leaves the functionality the same for traders lucky enough to interact with the .com api.

@sammchardy If you could take a look at this it would be great. I use the get_account_status function with the us tld and have had to maintain a patch to make get_account_status to work.

Thanks @OpenCoderX