rpc: Add ability to specify master args when creating proxy

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
phaul: Sanitize criu, img and htype initialization on local & remote sides

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
htype: Pass the htype tuple to both -- local and remote sides

This gets rid of htype.id call.

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
iter: Sanitize initialization

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>