STORE-394 Fix

This pull request fixes the following issue:

STORE-394:  Add date feild support URL: https://wso2.org/jira/browse/STORE-394

The fix involves the inclusion of a Date plugin to the Form Manager script.The plugin uses the jquery.datepick [1] script to render a date field and obtain the date value.

[1] jquery datepick script URL: http://keith-wood.name/datepick.html