ofproto_v1_0_parser: import ofproto_v1_0 as 'ofproto'

as proposed while ago, import ofproto_v1_0 with a version agnostic name
to reduce differences between parser modules.

the name 'ofproto' was chosen to match with ofproto_v1_4_parser.

update tests accordingly.
ofproto_v1_2_parser: import ofproto_v1_2 as 'ofproto'

as proposed while ago, import ofproto_v1_2 with a version agnostic name
to reduce differences between parser modules.

the name 'ofproto' was chosen to match with ofproto_v1_4_parser.

update tests accordingly.
ofproto_v1_3_parser: import ofproto_v1_3 as 'ofproto'

as proposed while ago, import ofproto_v1_3 with a version agnostic name
to reduce differences between parser modules.

the name 'ofproto' was chosen to match with ofproto_v1_4_parser.