Add support for Linux's browsers

Finally! :clap:

Closes #2
Fix gulpfile bump tasks

Remove references to files that did not exist in this repo. The gulpfile
was copied from another project and the references were there by
mistake.
Add node environment to .jshintrc
Remove duplicated use strict statements
Remove deprecated gulp.run() call

Use the current accepted `gulp.watch()` method for running scripts
instead.
Release 2.1.0