[TIMOB-321] iPhone: Long headers in custom GroupedViews don't display correctly

Long headers in custom GroupedViews don't display correctly when a text color is not specified.

The problem can be reproduced by making these changes to custom_grouped_view.html in KitchenSink:

1. In section 1, amend the header from Header to This grouped view provides an example of an unusually long header.
   
2. In section 1, omit the line which reads color:'white'.

When the color parameter is omitted, the start of the header is forced off the top of the screen and can't be seen.

The expected result is that which occurs when a text color is specified - i.e. the header is truncated and an ellipsis is added. (But note that there have been http://support.appcelerator.net/discussions/support/661-overlapping-text-in-groupedsection"> other requests for this behaviour to be modified e.g. by optionally text-wrapping instead of truncating.)

Examples and screenshots

http://support.appcelerator.net/discussions/titanium-mobile-discussion/1049-header-in-custom-grouped-view"> http://support.appcelerator.net/discussions/titanium-mobile-discuss...

http://support.appcelerator.net/discussions/titanium-mobile-discussion/1115-long-header-not-displaying-correctly-with-grouped-view"> http://support.appcelerator.net/discussions/titanium-mobile-discuss...

http://support.appcelerator.net/discussions/titanium-mobile-discussion/1131-since-upgrading-to-08-this-has-been-happening"> http://support.appcelerator.net/discussions/titanium-mobile-discuss...