CRM-12108 noticed type on 'skipDefault' was wrong
CRM-12108 noticed api.contribution_recur.frequency_interval needs to be mandatory
CRM-12108 noticed api.contribution_recur.start_date needs to be set or have a default - am defaulting to now
CRM-12108 tests on refactored PayPalProIPN, if CRM-12972 is fixed try catch can be removed & can update to check mail is sent
CRM-12108 refactore PayPalProIPN.php so that it can be called outside of a webtest & can be tested
CRM-12108 add code comments which explain why I couldn't make the test succeed without the try catch block - see CRM-12972 for user reports