Remove livereload cache buster param in extractId

When using [grunt-contrib-watch](https://github.com/gruntjs/grunt-contrib-watch) for livereload and using less.js during development causes the reloading of less styles to happen incorrectly.  Basically [tiny-lr](https://github.com/mklabs/tiny-lr) (used by grunt-contrib-watch) adds a query param to all the files it retrieves like "?livereload={{current time}}".  Less.js then uses that url to try to extract the id of the given less file and sees each one as unique instead of the appropriate file.

This causes the livereload/less combination to add the styles from the changed less file but not remove the old ones.  More discussion can be found here:
https://github.com/cgross/generator-cg-angular/issues/60

Credit for researching the issue and determining the fix goes to @bpartridge.