Add group notation - #33 improvement

[RodriguesZe]

Added support for Resource Groups, version based.

This implementation is nothing new. It's a combination of the solution provided by #33 and by the need raised in #41.

Basically, it allows having group annotation for a specific documentation version, instead of appearing by default in every version.

With this change, it's mandatory to have a version in the controller comments (see example below). Without it, the methods specified in the controller will not be considered, even if the right documentation version was added.

Following the tests already in place, here's an example of how the group and version resources can be used combined:

/**
 * User Photos Resource.
 *
 * @Group("User")
 * @Versions({"v1", "v2"})
 * @Resource("User Photos", uri="/users/{userId}/photos")
 * @Parameters({
 *      @Parameter("userId", description="ID of user who owns the photos.", type="integer", required=true)
 * })
 */
class UserPhotosResourceStub
{
    /**
     * Show all photos.
     *
     * Show all photos for a given user.
     *
     * @Get("/{?sort,order}")
     * @Parameters({
     *      @Parameter("sort", description="Column to sort by.", type="string", default="name"),
     *      @Parameter("order", description="Order of results, either `asc` or `desc`.", type="string", default="desc", members={
     *          @Member("asc", description="Ascending order."),
     *          @Member("desc", description="Descending order."),
     *      })
     * })
     * @Versions({"v1", "v2"})
     * @Response(200, body={
     *      {"id": 1, "name": "photo", "src": "path/to/cool/photo.jpg"}
     * })
     */
    public function index($userId)
    {
        //
    }
}

[philipborbon]

Will resource group be supported?