packaging: move backend/manager/dbscripts->packaging/dbscripts

dbscripts are plain files, copied as-is, not used during maven build.
placing these at packaging will ease installation and management.

move .gitignore entries to global .gitignore to simplify blind copy.

Change-Id: I0b4ecb8156970ac89505e165049c06afc6d86124
Signed-off-by: Alon Bar-Lev <alonbl@redhat.com>