Don't globally install grunt
Don't globally install grunt

Recent grunt-cli will attempt to install grunt as
well, but fail because the file already exists.
This failure causes further installation instructions
to not be executed.

Grunt, since 0.4, explicitly recommends against
installing grunt globally. grunt-cli should be global,
grunt should be installed locally.

See https://gruntjs.com/upgrading-from-0.3-to-0.4#grunt-0.3-notes

Change-Id: I5cd00bbd44c2856f38b5899fb2a6cb0e04467c65

wikimedia/mediawiki-vagrant,wikimedia/mediawiki-vagrant,wikimedia/mediawiki-vagrant,wikimedia/mediawiki-vagrant,wikimedia/mediawiki-vagrant,wikimedia/mediawiki-vagrant