Moved volume container definitions

I've placed the `application` and `data` directories into a `volumes`
subdirectory. The top level `data` directory is now used for storing the
data used by the database (and other, if any) containers. The `data`
directory has also been added to the `.gitignore` file to prevent
accidental pushing of user data.

volumes/application/Dockerfile

@@ -0,0 +1,7 @@
+FROM debian:jessie
+
+MAINTAINER Mahmoud Zalt <mahmoud@zalt.me>
+
+WORKDIR /var/www/laravel
+
+CMD ["true"]

volumes/data/Dockerfile

@@ -0,0 +1,5 @@
+FROM debian:jessie
+
+MAINTAINER Mahmoud Zalt <mahmoud@zalt.me>
+
+CMD ["true"]