Mentioning courses taken on coursera.org in the statement of purpose
I don't think it would necessarily hurt your application. However, if you have a limited number of words for your SOP, I think a better use of space would be to explain why exactly you want to obtain a degree in geoinformatics. Your Master's coursework will give you all the background (and probably more) that you need in the field, so it might be better to explain your motivation behind applying for the degree in the first place. Of course, if the Coursera course was a primary driver in your decision, that is highly relevant and should be mentioned.