Simplify browserify bundles with `require` module

I started work over the weekend to require modules within the dropchop source. This would be one of the first steps in removing the dependency on Gulp as we could run browserify as a npm one-liner rather than streaming each module through Gulp.

[mapsam]

@nickpeihl all of dropchop is currently written in the “module pattern” (not to be confused with npm modules) and I always find this article super helpful in how to organize code, globals, and share across files: http://www.adequatelygood.com/JavaScript-Module-Pattern-In-Depth.html

Introducing require and browserify may or may not require us to re-architect how dropchop is written.

[nickpeihl]

@wboykinm I don’t think so. You could probably add each of the turf modules to this array instead of the main turf library. It’s worth a try since this issue might take a while.