TIMOB-17157-Add a customized adapter to handle font

Added a customized adapter so that we can get the views to set the font.

https://jira.appcelerator.org/browse/TIMOB-17157
Right, but if you look at the current implementation of TiUILabel, when 'null' is passed in, we still process it. This PR will process 'null' values when at least one value is not null, which is inconsistent. We need to either process null values or not at all. I'd go with processing null values since we are already doing that in our other widgets.