OFStateManager: create a struct for cookie buckets

More fields will be added to this struct in the future.
OFStateManager: remove unused flow_id_hash_entry field
OFStateManager: update comments for ft_entry_t

Also moved and resized fields for better packing.
OFStateManager: remove unused query modes
OFStateManager: remove support for overlap checking

No sane controller would ever set this flag. It requires a linear scan through
the flowtable.
OFStateManager: remove support for restricting flow-delete and flow-stats on out-port

AFAIK no one ever used this feature.
Merge into master from pull request #172:
OFStateManager cleanup (https://github.com/floodlight/indigo/pull/172)