lvmetad enabled by default, add lvm2-activation-generator and related fixes
    
    - Add lvm2-activation-generator systemd generator to automatically
      systemd units to activate LVM2 volumes even if lvmetad is not
      This replaces lvm activation part of the former fedora-storage-init
      script that was included in the initscripts package before.
    - Enable lvmetad - the LVM metadata daemon by default.
    - Don't use lvmetad in lvm2-monitor.service ExecStop to avoid a systemd issue.
    - Remove dependency on fedora-storage-init.service in lvm2 systemd units.
    - Depend on lvm2-lvmetad.socket in lvm2-monitor.service systemd unit.
    - Init lvmetad lazily to avoid early socket access on config overrides.
    - Hardcode use_lvmetad=0 if cluster locking used and issue a warning  msg.
    - Fix dm_task_set_cookie to properly process udev flags if udev_sync disabled.