Initial implementation of custom table view rows.

[TIMOB-12788]
Fix layout issues with custom table view rows.

[TIMOB-12788]
Fix a bug which caused list items to disappear.

There appears to be a bug in Cascades if you try to setRoot()
on a control which was previously setRoot() on a different instance.
So to avoid this problem we wrap the row content in a container.
That container is always bound to the custom list view, so no need
to switch the root.

[TIMOB-12788]
Move implementation code for custom item out of header.

[TIMOB-12788]
Merge pull request #68 from joshthecoder/TIMOB-12788

[TIMOB-12788] BlackBerry: Support Custom Table View Rows