Add callback versions of some tests, split apps into another test context
Add callback versions of some tests, split apps into another test context

adamryman/splunk-sdk-javascript,splunk/splunk-sdk-javascript,splunk/splunk-sdk-javascript,adamryman/splunk-sdk-javascript,splunk/splunk-sdk-javascript,lowtalker/splunk-sdk-javascript,lowtalker/splunk-sdk-javascript