More Grunt updates:

* Add `_n_noop` to `grunt-pot` keyword check
* Remove grunt task `test` as PHPUnit tests are covered by grunt task `phpunit`
* Add grunt task `jstest` to run javascript tasks
* Add `grunt-checktextdomain` to `package.json` to check for missing or incorrect text-domain in gettext functions. See https://www.npmjs.org/package/grunt-checktextdomain
* Adds grunt task `checktextdomain` to `grunt build-release`
* Checks for the following keywords: `__:1,2d`, `_e:1,2d`, `_x:1,2c,3d`, `_n:1,2,4d`, `_ex:1,2c,3d`, `_nx:1,2,4c,5d`, `esc_attr__:1,2d`, `esc_attr_e:1,2d`, `esc_attr_x:1,2c,3d`, `esc_html__:1,2d`, `esc_html_e:1,2d`, `esc_html_x:1,2c,3d`, `_n_noop:1,2,3d`, `_nx_noop:1,2,3c,4d`
* Props netweb. See #2542.

git-svn-id: https://bbpress.svn.wordpress.org/trunk@5293 9866e705-20ec-0310-96e7-cbb4277adcfb