OSD: remove created argument from get_or_create_pg()

Signed-off-by: Samuel Just <sam.just@inktank.com>
OSD: make get_or_create_pg handle_pg_peering_evt

handle_pg_peering_evt() includes checking for splitting
and unlocking the pg.

Signed-off-by: Samuel Just <sam.just@inktank.com>
OSD: add pgid and res_map to DeletingState

Signed-off-by: Samuel Just <sam.just@inktank.com>
OSD: resurrect a parent if it splits into the pg we want to create

Signed-off-by: Samuel Just <sam.just@inktank.com>
OSD: create collection in handle_pg_create

Signed-off-by: Samuel Just <sam.just@inktank.com>
lock the old_pg_state
more locking