Bump NPM package versions in package.json
"grunt-contrib-copy": "~0.6.0" -> "~0.7.0"
"grunt-sass": "~0.14.1" -> "~0.16.0"
"grunt-wp-i18n": "~0.4.8" -> "~0.4.9"
Requires npm install to update packages and dependencies

git-svn-id: https://bbpress.svn.wordpress.org/trunk@5555 9866e705-20ec-0310-96e7-cbb4277adcfb