Fixes #3: Added non-buffertools dependent entry point.

[n1k0]

Refs #3. Updated usage docs:

usage

// vanilla
var deepEqual = require('deeper')

if (!deepEqual(obj1, obj2)) console.log("yay! diversity!");

If you don't plan on depending on buffertools, simply require
deeper/no-buffertools instead of deeper, so your bundler won't yell at you:

var deepEqual = require('deeper/no-buffertools')

if (!deepEqual(obj1, obj2)) console.log("yay! diversity!");