Fix archive tests so that they don't use tarfile
Fix archive tests so that they don't use tarfile

tarfile strips './' off the beginning of paths in python 2.6 but not in
2.7, making it very difficult to consistently test archive paths between
the two.  So we just stopped using it for our tests since we weren't
using it in our implementation anyways.

RedHatInsights/insights-core,RedHatInsights/insights-core