Floodlight subtree merge

Issue #406 continued

    1) Ability to ask for last N events
    2) Events now show up with most-recent-first
    3) Including ThreadName as one of the columns
    4) Ensuring moduleName and eventNames in URL do not include '/'
    5) Removing dead code in Event.java
    6) Updating unit tests

accomodating the CLI)

Issue #406

BSC-3970 ARP packet parsing exception causes switch disconnect (https://github.com/bigswitch/bigswitchcontroller/pull/3837)

Removed App Loader

change flow mod event names to being delimited by "-"

Flush Events Explicitly in DeviceManager outside packet-in pipeline (https://github.com/bigswitch/bigswitchcontroller/pull/3828)

Flow Mod Events (https://github.com/bigswitch/bigswitchcontroller/pull/3816)

debug events cli forces some columns to be left-most columns (https://github.com/bigswitch/bigswitchcontroller/pull/3798)

BSC-3926. Set switch's connectedSince when the switch is actually connected. Set to null otherwise. (https://github.com/bigswitch/bigswitchcontroller/pull/3770)

as the left-most columns

Removing event-history (replaced by debug-events) (https://github.com/bigswitch/bigswitchcontroller/pull/3791)

o show openflow cluster count with/without tunnels
o show external port count for each external cluster