Use print function rather than print statement

This is for Python 3 compatibility, since Python 3 does not support
the print statement, only the print function.  (Python 2.6 and 2.7
support both, depending on whether a __future__ import is used.)

Paths containing "xen" were left alone, because of comments in a
couple of the files indicating that the XenServer code needed to be
compatible with Python 2.4.

Fixes bug 1226943

Change-Id: I23b804a4d99500b4acf81dd19645ab06dfcc9f1c
Merge "Use print function rather than print statement"