Don't make objCopy crash on non-objects

Looks to be related to #198, #150, and #100. For non-object values, null, or undefined (loose `==` checking) it simply returns that value rather than trying to call Object.keys and crashing. May alternately be better to use a dedicated module, like lodash, for cloning, as the full process of creating a true replica is [rather extensive](https://github.com/lodash/lodash/blob/2.4.1/dist/lodash.compat.js#L1023-L1101).