Merge pull request #253 from pulp/rbarlow-test_iso_import_units

Assert that ISOImporter.import_units returns the imported units.
Merge pull request #255 from pulp/jconnor-test-custom-metadata-fix

changed unit test to use glob instead of yum utility
Test the new calculate_{size,checksum}() methods in common.models.
Add some additional tests to test_common_models.py.
Merge branch 'rbarlow-test_common_models_calculates'