Fixes #2140 print statement syntax

Changed to ([  ]) so that number is printed, instead of a generator
Merge pull request #2196 from cayci/rework_issue2140

Rework issue2140
doc: extended bind example
doc: added refernce to bind method for more info
Merge branch 'master' of https://github.com/kivy/kivy

Merging master
urlrequest: fix if the result cannot be decoded (like image/png)
doc: clarified object binding