Minimal landing page

[nuest]

Lacking the time to integrate the explorer, I suggest to include a minimal landing page at /api, so that e.g. http://sensorweb.demo.52north.org/sensorwebclient-webapp-stable/api/ contains at least the following information:

• deployed software version of the API
• API endpoint
• link to documentation at http://52north.github.io/timeseries-api/
• link to source code
• a few example GET requests

[Amritanshu02]

Hello! I would like to work upon this issue, could you suggest me where to start?