Added OSS licence
Changed the licence URL in all NuSpec files.
Added Questions section

because people seem unsure where to ask questions.
Added testimonial from Florian Hötzinger.
Changed local link to testimonials,

since it seems that GitHub auto-generates local anchors from headlines, e.g. "#who-uses-autofixture"...
Added testimonial.
Fixed links in testimonial.
Added testimonial.