'#1432 date editor'

PR contains code changes for date editor, the major changes are:
1. Support added for date editor.
2. Directive added to support 'input[date]' in Angular 2.0.
3. Change in 500_complex.json is to remove a space in date values, javascript date parsing was failing because of that space.
4. Refactoring: Renaming 'uiGridTextEditor' to 'uiGridEditor'.
5. Refactoring: Using single template 'cellEditor.html' instead of 4 different templates for number, booleans, date and string.
6. I was unable to write test cases for dynamically setting type="{{inputType}}", this is creating issue with jQuery. It says that jQuery can not change 'type' attribute in DOM, but this dynamically setting 'type' is otherwise working fine in code.