<check-sources> Clean up long lines, unpythonic names

First big pass with pylint to bring code close to PEP 8 style. Should
be no logical changes other than `OpenShiftCheckSources._init_yumbase`
returning the yumbase object instead of setting `self.yum_base`
directly.
Merge pull request #168 from dobbymoodge/check-sources-cleanup

<check-sources> Clean up long lines, unpythonic names, etc.