Provide an Android App

[dbaelz]

Currently, Open Sense is just a widget and a configuration screen. To integrate more features provided by the openSenseMap-API the project should consist of a typical Android app.

This issue is intended as a collection of ideas and base-issue for the later implementation. Please feel free to post your ideas, input and toughs about this topic.

Some base features:

• Info box to see the sensor data for my preferred senseBox in the app
• Search and view the sensor data of every senseBox
• Information about den openSenseMap project and links to the website
• Show the history of sensor data (see show history plots incl. mean values #12)