Update CONTRIBUTING.md and README.md

[markuspf]

These two files are to be sharpened and updated to our needs, preferably really soon.

[olexandr-konovalov]

These files are written in the Markdown format, and you may find its short description in GitHub help pages here.

[olexandr-konovalov]

I am revising these two files in my fork and will submit a pull request for you to review later.

[olexandr-konovalov]

You may see my changes in olexandr-konovalov@081b575. Any other suggestions before I will submit a pull request? I am also working on a PDF "Quickstart" document for developers, which we may put on Wiki

[markuspf]

Closed with #3