One more change to be grunt-0.4.0 compatible

[larsthorup]

When using grunt-qunit-cov-0.3.0 with grunt-0.4.0 I get the following error:

Fatal error: Object #<Object> has no method 'expandFileURLs'

This pull-request attempts to fix this, following the advice on https://github.com/gruntjs/grunt/wiki/Upgrading-from-0.3-to-0.4.

[afonsof]

@larsthorup, my builds using grunt-qunit-cov with new 0.4 grunt is throwing an error. I know in this new version, 'utils' was deprecated and 'util' become to be used. However I've found this error everywhere 'util' is mentioned:

P:\webbers\projects\Gbwcd\trunk\src\Gbwcd\Scripts\gbwcd\node_modules\grunt-qunit-cov\tasks\lib\phantomjs.js:15
        return grunt.util.spawn(
                          ^
TypeError: Cannot call method 'spawn' of undefined
    at exports.phantomjs (P:\webbers\projects\Gbwcd\trunk\src\Gbwcd\Scripts\gbwcd\node_modules\grunt-qunit-cov\tasks\lib\phantomjs.js:15:27)
    at module.exports.grunt.registerMultiTask.jscoverage.done (P:\webbers\projects\Gbwcd\trunk\src\Gbwcd\Scripts\gbwcd\node_modules\grunt-qunit-cov\tasks\qunit-
cov.js:302:21)
    at async.forEachSeries.iterate (P:\webbers\projects\Gbwcd\trunk\src\Gbwcd\Scripts\gbwcd\node_modules\grunt\node_modules\async\lib\async.js:108:13)
    at Object.async.forEachSeries (P:\webbers\projects\Gbwcd\trunk\src\Gbwcd\Scripts\gbwcd\node_modules\grunt\node_modules\async\lib\async.js:124:9)
    at Object.module.exports.grunt.registerMultiTask.jscoverage.done (P:\webbers\projects\Gbwcd\trunk\src\Gbwcd\Scripts\gbwcd\node_modules\grunt-qunit-cov\tasks
\qunit-cov.js:231:35)
    at exports.jscoverage (P:\webbers\projects\Gbwcd\trunk\src\Gbwcd\Scripts\gbwcd\node_modules\grunt-qunit-cov\tasks\lib\jscoverage.js:25:36)
    at ChildProcess.utils.spawn (P:\webbers\projects\Gbwcd\trunk\src\Gbwcd\Scripts\gbwcd\node_modules\grunt\lib\grunt\utils.js:110:5)
    at ChildProcess.EventEmitter.emit (events.js:91:17)
    at maybeClose (child_process.js:638:16)
    at Process._handle.onexit (child_process.js:680:5)

Do you know why this problem is happening? I'm sure I'm using grunt 0.4