Introduce new signature for both `dgram.createSocket` method and
`dgram.Socket` constructor:
dgram.createSocket(options, [listener])
Options should contain `type` property and may contain `reuseAddr`
property. When `reuseAddr` is `true` - SO_REUSEADDR will be issued on
socket on bind.
fix#7415
Signed-off-by: Fedor Indutny <fedor@indutny.com>