Made `commands` in config plugin executable to use with pluginhook.
Merge pull request #258 from mikexstudios/master

Made `commands` in config plugin executable to use with pluginhook.
Allow bootstraping Vagrant VM with a cached stack tarball
Merge branch 'support-for-cached-stack-tarball-on-vagrant'

* support-for-cached-stack-tarball-on-vagrant:
  Allow bootstraping Vagrant VM with a cached stack tarball
Introduce URL for app. Plugins can override this.

fixes #242
Enable 'nginx reload' support for git and dokku user. Refs #124. Refs #186
New command: dokku delete <app>

Two new hooks are implemented:

- pre-delete $APP
- post-delete $APP

The following are implemented in the `post-delete` hook:

- `$APP` directory deletion (00_dokku-standard)
- nginx reload (nginx-vhosts)

The following command can be executed by either the `dokku` or `git` user as `sudo`:

    sudo /etc/init.d/nginx reload

Refs #124
Closes #186
Merge pull request #262 from josegonzalez/app-deletion

App deletion