Fix 'print' and 'file' for python 3.5 scripts in libbeat

[radoondas]

This PR fixes (in my case) issues with python scripts. I was unable to run 'make update' unless I fixed scripts the way as in commit. Environment created in my beat was with python3.5.
Is this a valid fix?

[elasticsearch-release]

Jenkins standing by to test this. If you aren't a maintainer, you can ignore this comment. Someone with commit access, please review this and clear it for Jenkins to run; then say 'jenkins, test it'.

[elasticsearch-release]

Jenkins standing by to test this. If you aren't a maintainer, you can ignore this comment. Someone with commit access, please review this and clear it for Jenkins to run; then say 'jenkins, test it'.

[ruflin]

I think most of us running everything in Python 2.7.x. It would be nice if the above fixes make it compatible with both version. I will probably have to test this one manually :-)

[radoondas]

I thought so.
I still noticed that there were in one 'print' call parenthesis and in the other not. And the same with 'file' vs 'open' call. I will be happy if you test it when you have time. :)

[ruflin]

Seems to work fine under python 2.7. Merging.