Check for existing email and mobile accounts

Imports from niche.com need to check for existing email and mobile accounts as they are not billable.

Add calls to:
- $MailChimp->call("/lists/member-info"
- $MobileCommons->profile
Should this be `$existingStatus = $this->checkExistingAccount($data, $existingStatus)`? Because you're returning the modified array from this function.

Alternatively, you could not return anything from `checkExistingAccount` and pass by reference instead: `private function checkExistingAccount($data, &$existingStatus)`.