1001169: fix pythonic empty string identity problems
Merge pull request #751 from candlepin/ckozak/auto_attach_servicelevel

1001169: fix pythonic empty string identity problems
rev min python version for "make stylish" to 2.6

Or more accurately, set the minimum version to
complain about to 2.7. ie, let python 2.6
features pass versionlint.
Merge pull request #755 from candlepin/alikins/woohoo_python_2_6

rev min python version for "make stylish" to 2.6