classifier: Make versioning more explicit.

classifier: Make versioning more explicit.

Now that struct cls_match has 'add_version' the 'version' in cls_match
was largely redundant.  Remove 'version' from struct cls_rule, and add
it to function prototypes that need it.  This makes versioning more
explicit (or less indirect) in the API.

Suggested-by: Ben Pfaff <blp@nicira.com>
Signed-off-by: Jarno Rajahalme <jrajahalme@nicira.com>
Acked-by: Ben Pfaff <blp@nicira.com>