Aligned project with Underscore/Lodash

- I updated the documentation so it was easier to digest
- I updated the folder structure so that methods that were previously in 'chaining' are now in 'functions' simply because they are not necessarily chainable methods
- I aligned the project with Underscore/Lodashes documentation, in that this repo is not aiming for feature parity with either library, but that those features will ultimately be supported as it is improved
- I added the `now()` method
- I updated the `flatten()` method, so that is was 1:1 with Underscore's implementation