WIP - Make 'dist' path configurable via option

This mimics the `grunt watch:dev --target="D:\MySite"` option from Archetype, but with a simpler approach (thanks @taylorsmith)

Instead of adding new tasks, we're making the `/dist/` directory configurable, so existing tasks can be used easily (ie, `grunt` or `grunt watch`)

Examples:

`grunt --target="D:\MySite"`

`grunt watch --target="D:\MySite"`

Note that we're now building using the full folder structure (`App_Plugins/<name>/<files>`) instead of a flat structure, which should make deployment a bit easier, especially when we add other folders like `/bin/`

Implements #6