Updates gulp-plumber dependency.
Updates gulp-plumber dependency.

Resolves #169

alex-wilmer/generator-babel-boilerplate,lanetix/generator-lanetix-script,babel/generator-babel-boilerplate,babel/babel-library-boilerplate,babel/babel-library-boilerplate,babel/generator-babel-boilerplate,alex-wilmer/generator-babel-boilerplate