engine : Generate CommandContext on engine restart

After engine restart the command context map
in memory is empty and we need to regenerate
the CommandContexts for those commands that do
not have a constructor with out CommandContext

Change-Id: I641802c6e0e05abaa2ecd84d0718f0d95ab59d9e
Bug-Url: https://bugzilla.redhat.com/1115127
Signed-off-by: Ravi Nori <rnori@redhat.com>