Hide Prompt Above Input Box

Problem/Motivation

The text 'Enter the terms you wish to search for.' that sits above the default search input box should be either configurable, or hideable.

It could be hidden using a custom theme hook_form_alter(), but this would probably be a useful feature of the module

Proposed resolution

The attached patch is the simplest approach where the default prompt "Enter the terms you wish to search for." can be shown or hidden via a simple boolean toggle.

This could easily be extended to allow the prompt text to be customised.