Replace lodash with native ES5 functions and ES5-based implementations to reduce lib size

So, that's a PR for #91
I went a bit overboard and removed a lodash completely. 
That reduced the size of the lib to 24kb normal size or 8.4kb minified.

Test are all passing normally, coverage did fell a bit though because of the functions that I'd added to replace lodash stuff (e.g. _.clone, _.isEqual), but not too much.

Let me know if that's too much or if there are more additions needed :)