Enhancement: Add the store service

Tags: store

* Enhancement - Add version command: [#226](https://github.com/owncloud/product/issues/226)
* Bugfix - Removed code from other service: [#7](https://github.com/owncloud/ocis-store/pull/7)
* Bugfix - Build docker images with alpine:latest instead of alpine:edge: [#5](https://github.com/owncloud/ocis-store/pull/5)
* Change - Initial release of basic version: [#1](https://github.com/owncloud/ocis-store/pull/1)

https://github.com/owncloud/product/issues/244
