Use HTTP base to serve src files

I needed the ability to host tests without knowing the files.

There seems to be a limitation currently: one can provide a list of explicit URLs or the usual "src" matchers. I have added to the task so that if there is an "httpBase" option present, all src files are prefixed with that base.

My config now looks like:

    module.exports = function(grunt) {
    	grunt.initConfig ({
    		connect: {
    			options: {
    				base: '.',
    				port: 8001
    			},
    			test: {
    				options: {
    					keepalive: false
    				}
    			}
    		},
    		qunit: {
    			tests: {
    				options: {
    					httpBase: 'http://localhost:8001'
    				},
    				src: 'devel/tests/*.html'
    			}
    		}
    ...

That will:
1) start an HTTP server, hosting the QUnit HTML documents
2) expand the src files to ['devel/tests/TestSomething.html', 'devel/tests/TestAnother.html']
3) Add to the `urls` array: ['http://localhost:8001/devel/tests/TestSomething.html', 'http://localhost:8001/devel/tests/TestAnother.html']
4) Run the tests as normal