When browserifying anything that depends on React, don't bundle another
copy of React in the file. There might be some other common dependencies
that we should include here.
* Remove gulp, replace with custom scripts
* Symlink entire dirs where possible (fixes#1232)
* Significantly speed up subsequent builds (fixes#1238)
* Watch process now observes new/removed files, not only changed
* Add ignoreMask, exclude all files with names starting with a #
* Better logging during builds
* Update travis.yml to use new, non-gulp-based build