RSTP implementation core files (IEEE 802.1D)
RSTP interaction with OVS, documentation and tests.
rstp: Fix MAC learning tables flushing.
rstp: Fixed rstp BPDU padding. Removed unused code in tx_rstp(), tx_config(), tx_tcn().
ofproto-dpif: Fix segfault removing port when RSTP is enabled.

Reported-by: Sridhar Samudrala <samudrala.sridhar@gmail.com>