contextData should accept JSON properties

[marcus-robinson]

As it stands, the contextData property forces the developer to provide values as XML, like this:

var callData = { pageName: 'analytics-di-test', visitorID: 'myvisitorId123123123123', contextData: '<sc_contextDataTest>my context data test</sc_contextDataTest>' };

It is very confusing for a Node library to ask developers to provide XML strings. JSON is the object notation for JavaScript and it should be the library's job to convert a developer's context data JSON object into the required XML string that the AA API expects, instead of putting this burden on the developer.

[davidbenge]

much better idea
way more natural