Mention Modernizr 3 in README
Merge pull request #13 from backflip/readme

Mention usage of Modernizr 3 in README
Define Modernizr as a peerDependency
Update dependency paths.
Merge branch 'feature/modernizr-as-peer-dependency' of github.com:doctyper/gulp-modernizr into feature/modernizr-as-peer-dependency