Revise 'Delete Index' button for consistency and UI tweaks

These two commits make the "Delete Index" button behave correctly graphically/layout wise on the Administration tab

* Added missing btn-block class to Delete Index button

* Removed alert icon from Delete Index button for consistency in other buttons on the same UI

This also resolves a screen resizing problem where the button may not always be flood-filling/stretching to the sides

Revise fix for Issue #44