sie-update: added cache code
sie-update: Added cache_dir parameters to http-related functions
sie-update: Implemented cache_dir in update function
sie-update: Switched from uuid to filename from parsed URL
sie-update: Implemented cache freshness check
sie-update: set default of 1 week for cache age
sie-update: made cache files readable.  they are public anyway
sie-update: refactored do_update call to enable daemonization
sie-update: implemented daemonization
sie-update: Handled error conditions with raise and not sys.exit for daemon
sie-update: Handle unhandled exceptions in the daemon so we don't die
sie-update: remove debugging print