Remove existing livereload config.
Remove existing serve and open tasks.
Add Browser-Sync.

This replaces:  serve and open tasks, livereload

As of this commit, index.html is not served (because it isn't in
build/).
Move index.html out of root and add copy task.
Make `watch` run after `build`, not simultaneously.

This makes the `watch` have the `build` task as a dependency.  While
this would not be ideal for a large project, I think it should be OK for
most projects (since gulp is fast; this wouldn't work for me in grunt).

I imagine an end-user of this repo will have much customized the gulp
configuration anyway by the time their project is large enough for this
to be a problem.
Move browserSync to its own task
Fix browserify/watchify recompling
Merge pull request #18 from greypants/fix-livereload

Replace livereload with browser-sync