Use print() function in both Python 2 and Python 3

[cclauss]

Legacy print statements are syntax errors in Python 3 but print() function works as expected in both Python 2 and Python 3.

Also, use with open() as context manager syntax to automate file.close() even in the face of exceptions.

[cclauss]

Fixing these syntax errors would be helpful because this code is vendored into:

• https://github.com/kubernetes/frakti
• https://github.com/kubernetes/kops

[ugorji]

@cclauss

Thanks for the fix. I am not too versed with the python 2 vs 3 differences, so had to do some research first before accepting.

[cclauss]

No problems. Thanks for doing this.