OF-2516: Show session TX/RX instead of prio on admin console
The admin console's "Session Summary" page lists all client sessions and shows some data.
With this commit, the 'priority' value (which is hardly used) is replaced by TX and RX values, that give an indication of activity (as it shows the amount of stanzas exchanged between client and server).
OF-2517: Fix 'packet sent' count for BOSH connections
Openfire keeps track of the amount of stanzas sent through a connection. For BOSH connections, the outgoing count was never updated. This is fixed in this commit.
This change also ensures that a 'last activity' field is updated more frequently. This could improve the stability of BOSH connections.
