New sandbox project supporting custom fields integration for campaignmonitor_user

I've created a new sandbox project to allow for custom fields integration for the campaignmonitor_user module, and a few additional configuration options - it's work in progress at the moment but so far has necessitated a couple of extra methods on the CampaignMonitor class

Sandbox project here:
https://www.drupal.org/sandbox/somatick/2863080

I will attach a patch for the new methods