Update Python build scripts to use the print function

[alexwlchan]

In Python 3, 'print' was changed from a statement to a function. Using
the future module allows scripts to use print function whether
running with Python 2.6+ or Python 3.x. This commit changes as many
instances of print as I could find to use the print function and the
future module.

This is part of ongoing work to get the Python scripts running under
both Python 2 and 3; see PR #90.

[modocache]

Thanks for continuing to push this through!! 👍

How does this pull request relate to #90? You mentioned you'd split up #90, but this pull request is even larger than that one.

[alexwlchan]

@modocache Two differences:

• The original PR was just looking for files that ended in *.py, which turns out not to be a good indicator of whether a file uses Python. I missed a lot of stuff. Now I’m just grepping for anything that looks like a print statement.
• The original PR was an attempt to get a clean run of all scripts against Python 3, which involves a substantial number of changes. This is a single, specific change that is hopefully easier to review.

[modocache]

Ah, gotcha. Well, all the changes look good to me!! Looks like you have a merge conflict, though.

[alexwlchan]

Rebased; merged conflicts fixed.

[gribozavr]

LGTM, tested on Ubuntu 14.04 and OS X.

[practicalswift]

@alexwlchan This is what I've used to find all Python files in the repo:

(git grep '#.*python'; find . -name '*.py' -type f) | grep -v .gitignore | sed 's|^./||g' | cut -f1 -d: | sort | uniq

Nice work cleaning up BTW! :-)