Auto-expand glob patterns for ease of use

[djfarrelly]

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/*.*