Update README.md, centered screenshot!

I think screenshot is better when it is centered.
Merge pull request #85 from MaciejCzyzewski/patch-2

Update README.md, centered screenshot!
Update README.md
Initial commit
slike
Merge branch 'master' of https://github.com/spojipoliticare/igra

Conflicts:
	README.md
Merge branch 'gh-pages'
Create README.md
Update README.md
Merge branch 'gh-pages'
font size
Merge branch 'gh-pages'
Merge branch 'master' of https://github.com/spojipoliticare/igra
Merge branch 'gh-pages'
Merge branch 'gh-pages'
buttons