Add link to execute the guide in a browser IDE (using Codenvy)

It's nice to see all the steps that we have to do, but it requires for example
- JDK 1.8 or later
- Gradle 2.3+ or Maven 3.0+
- git to clone the project or download and extract a zip file

whereas here, by using the following button, we only have to click on it ("Workspace Developer" button)
then we can try and develop spring rest service from the web browser.

Prepare guide for "depoy on PWS" feature

* push app artifact on S3 in CI script
* add a metadata file "run-on-pws.json" for the deploy agent
to read the app configuration from

Fixes gh-37

Fix typo

RestController Annotation Typo

Link was broken due to missing 's' i.e. **http://docs.spring.io/spring/doc** v **docs**

Resolves #32

Fixes gh-26