hawkey: Allow packages to change architecture when updating

Checking the arch+name was preventing pitivi from going noarch->x86_64.
Assume a cache-age of 'any' by default when using pkcon
hawkey: if a specified a specific cache-age then do not use the sack cache

This ensures we don't return cached readings when the user has requested up-to-date data.
hawkey: Use the cache age in deciding when to download new metadata
trivial: Remove some header functions that never got stubbed
hawkey: Run GetDetails() in a thread to avoid blocking the daemon
Add a new method GetDetailsLocal to get details about local packages
hawkey: Implement GetDetailsLocal
trivial: Fix up a debug typo
Return an error if a client tries to execute an unknown method
Katja: Add header files to the Makefile
Katja: Parse MANIFEST.bz2
hawkey: Save the previously downloaded packages when refreshing the cache
trivial: Return a sensible error when doing GetDetailsLocal('')