build mocha.js using browserify

[jonathanong]

first attempt to building mocha.js with browserify instead of all the custom stuff.

• i'm not sure what support/tail does, but i haven't incldued it in the build. still need to do that.
• the previous mocha require() didn't include mocha's dependencies, but browserify does, making the build too big. not sure how to disable them all without wanting to kill myself. i'm thinking just to create a separate browser entry point that doesn't require all the reporters

help would be appreciated because i'm no browserify expert

[rstacruz]

this project might be worth looking at: https://github.com/rstacruz/jsfuse

...it's ilke browserify, but lacks support for node_modules and such.