Fixes 2.6 compatibility of numerous files

Many pieces of example code or other utility modules were trying to
import print_statement from future, which does not exist. What the
developers probably meant was print_function (in common use elsewhere in
the repository).

This branch makes it so that compileall succeeds on all .py files in the
repo.
Merge pull request #591 from jolynch/compileall_fixes

Fixes 2.6 compatibility of numerous utility/example files