When getting blocking_applications from an Apple update dist file, de-dup the list of application-ids before finding matching applications.
Renamed updatecheck.getAppleUpdateMetaData to updatecheck.getPrimaryManifestCatalogs to reflect actual function; added function parameter to specify whether or not the primary client manifest and catalogs should be re-downloaded before parsing for apple_update_metadata

Additionally, ensure that MACHINE dict is populated regardless of the
runtype as it may impact how a primary manifest is discovered.
Minor code clean-up, no functional changes
Updated appleupdates_test.py to match changes in appleupdates.py