feat: make it possible to omit glob dependency - #192

I've got things ready to go on the Node.js side once this is merged.

@iansu a couple thoughts for you:

1. perhaps rename your PR on Node.js to something along the lines of fs: add fs.rmtree, and then in the description of your PR, point out that you're vendoring rimraf based on discussions with Myles.
2. with regards to tests for rmtree, we should probably make an effort to test all the same cases demonstrated in test/basic.js.
3. I'm excited about this; I think vendoring rimraf is a good start ... over time, I'd advocate we potentially solve more of rimraf's use-case at a lower level., e.g., in libuv.

@bcoe as soon as this is merged I'll submit my updated PR and update the title and description. Then I'll start working on adding additional testcases. test/basic.js does look like a good baseline.

Landed and published on v2.7.0. Thanks!

@iansu Given that the tests in this module are rather shoddy, I wouldn't recommend using them as anything but a starting point. Patches welcome to add test coverage :)

@isaacs Thanks for releasing this! I'll see if there are any test improvements we can contribute back.