Merge underscore.string.fp

[esamattis]

https://github.com/stoeffel/underscore.string.fp

Following the footsteps of Lodash v4.

Make this work

import {trim} from "underscore.string/fp";

var foo = trim("_")("_foo_");
expect(foo).toBe("foo");

Precompiled files for cherry-picking would be cool too

import trim from "underscore.string/fp/trim";

Maybe as a npm prepublish script.

Like in Lodash vNext

[stoeffel]

This would be awesome :+1:

[stoeffel]

How should we handle variadic functions like f.e. camelize?

[daedalus28]

This would be great for us too. Variadic functions should work the same way as lodash, and take an array or be split into multiple methods.