Auto-expand glob patterns for ease of use

### Purpose
Globs in golang work differently the globs have worked in popular node.js libraries like gulp. To make the usage of this simpler we could make `/**/*.jpg` also look in the first level dir for `*.jpg` files.

### Example
```
public/img/**/**/*.*
```
Turns into this automatically, resulting in a more shorter usage:
```
public/img/**/**/*.*
public/img/**/*.*
public/img/*.*
```