FIX: ViewableData wasn't setting values when using default cast

It looks like this was simply overlooked.  I ran the full framework tests suite and not a single test executed this branch of code.  I added a test for it and then fixed it.  It's a fairly trivial fix.  Templates were calling hasValue, and getting true (as expected), but then when they called obj for the same field they were getting back a StringField (Text to be more specific) that had no value set on it.