[TIMOB-1187] Selected state for tableView with single row has square corners on bottom

Related to ticket #433, mobileSDK 1.3.2, iOS 4

When you have a tableView with one row (or a tableview where the first row is separated from the second row by a Header) the selected state only has curves on the top of the row, while the bottom of the row is square. Looking at the fix for 433, my guess is that you need a 4th state (TiCellBackgroundViewPositionSingle perhaps) with curved top and bottom.

screenshot one (single_row.png) is a tableView with a single row
screenshot two (multi_rows.png) is a tableView where the second row has a blank header to achieve the separation

---

// create table view data object
var data = [
    {title:'Score Game', hasChild:true, test:'score.js', header:'Header text',
        leftImage: 'images/13-target.png'},
    {title:'Settings', hasChild:true, test:'../examples/table_view_perf.js', header:'',
        leftImage: 'images/20-gear2.png'},
    {title:'Help', hasChild:true, test:'../examples/table_view_perf.js',
        leftImage: 'images/90-lifebuoy.png'},
    {title:'Cornhole Rules', hasChild:true, url:'rules.html',
        leftImage: 'images/96-book.png'}
];