Added Slim Framework

How I did on Slim:

$app->group('/v1', function () use ($app) {
    $app->get('/accounts', function () use ($app) {
        // query database for all accounts
    });

    $app->get('/accounts/:id', function ($id) use ($app) {
        // query database using $id
    });
});
Merge pull request #423 from diego-vieira/patch-2

Added Slim Framework