Update browserify, browserify gulp task, and various dependencies.

I updated browserify to the lastest version and changed the browserify gulp task according to what you suggested in Issue#20. In order for browserify 5.10.1 to work, I updated browserify-shim and watchify. I also updated browser-sync and hbsfy. Did a test run, made a few changes to check if things changed, and everything checked out.

References:
https://github.com/greypants/gulp-starter/issues/20
https://github.com/thlorenz/browserify-shim/commit/461ec21c2a9b9f1d6f706eb7ca62b20113ab58eb