Add active re-syncing of information in the syscache daemon.
It will resync if:
1) A sync is not already running
2) A pkg database is changed (local or repo files)
3) A pc-systemflag was set

During a resync, it will actively check each jail/system component first and only resync that portion if needed. This makes re-syncs extremely fast, as it only updates what changed.
Merge branch 'master' of github.com:pcbsd/pcbsd