relax print_qiime_config.py python version check

Is now okay with any python versions >= 2.7.0 and < 3.0.0. Also supports python
version strings like the kind found in Miniconda's python, e.g.:

Python 2.7.6 :: Continuum Analytics, Inc.

Fixes #1391.
Merge pull request #1392 from jrrideout/issue-1391

relax print_qiime_config.py python version check