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

AUTHORS

@@ -3,8 +3,10 @@
 #
 Alexander <iam.asm89@gmail.com>
 Alexander Beletsky <alexander.beletsky@gmail.com>
+Alexis Gavoty <kload@kload.fr>
 Felipe Coury <felipe.coury@gmail.com>
 Jeff Lindsay <progrium@gmail.com>
+Jose Diaz-Gonzalez <dokku@josediazgonzalez.com>
 Leo Unbekandt <leo@unbekandt.eu>
 Luigi Maselli <grigio.org@gmail.com>
 Martin Weiss <kornnflake@gmail.com>