BF: prepare use of print for Python 3
BF: prepare use of print for Python 3

Getting Python 3-like error for print statement - use print function
instead.

arokem/nipy,alexis-roche/register,arokem/nipy,alexis-roche/nireg,alexis-roche/register,alexis-roche/nipy,alexis-roche/nipy,alexis-roche/nipy,nipy/nireg,alexis-roche/nireg,alexis-roche/niseg,alexis-roche/nipy,alexis-roche/niseg,arokem/nipy,arokem/nipy,nipy/nireg,alexis-roche/register