Feature : Expandable source file paths

This PR adds support for grunt paths expansion (as in grunt-contrib-copy).
With this feature, users are now able to specify expandable paths using [grunt.file.expand-comprehensible](http://gruntjs.com/api/grunt.file#grunt.file.expand) format.

For example the config :
```js
packageSpecific: {
    'jquery-ui': {
        files: [
            'ui/minified/jquery-ui.min.js',
            'themes/base/minified/**'
        ]
    }
},
```
can be used to deploy all files from the folder **themes/base/minified**, including subfolders and keeping the hierarchy.

It is also possible to flatten the dest hierarchy using the new setting **keepExpandedHierarchy=false** either from global or packageSpecific options.

Note this PR include the previous one (#27)