Updated to v1.5.1

- Added `maxRowsAllowed` option and `maxNumRowsReached` callback
function to limit the number of rows allowed.
(Thanks iannos for suggestion)
- Added `maintainScroll` option to scroll the page after appended or
removed last row.
(Thanks iannos for suggestion)
- Removed unnecessary coding so that `appendGrid` requires jQuery UI
Core, Widget and Button components only for all standard features. But
you will not able to use Datepicker or other jQuery UI widgets.