Expose interface that accepts minimatch instance instead of glob instanc...

Hi fractals,
I'm working on a fake file system based on the awesome vinyl. The new babe is called `[vinyl-fs-mock](https://github.com/timnew/vinyl-fs-mock)`, which can be used tests of  `gulp` plugins. 

I wish that sooner or later, we can test `gulp` plugin or any code based on `vinyl` and `vinyl-fs` stream without dependent on real file fixtures. The goal of this project could be similar to your guys' [vinyl-fs-tree](https://github.com/wearefractal/vinyl-fs-tree), which doesn't look like a finished project and is not as flexible as I expected.

Now I'm working on the glob support part, to make it as much compatible with `gulp` as possible. The implementation has been almost done. I'm dealing with some path and base path issue. The glob2base is likely to be used. 

The issue I met is that I only depends on `minimatch` but `glob`, so I wish `glob2base` publish a interface for `minimatch` instead as well as `glob` 

can you do this in two separate lines? not a fan of the multi assignments