Start clipboard monitor functionality

Added the basics of the clipboard monitor functionality with usage
messages and stuff like that. Lots more to do.
Merge branch 'upstream/master' into clipboard_monitor

Conflicts:
	lib/rex/post/meterpreter/ui/console/command_dispatcher/extapi/clipboard.rb
More work on the clipboard monitor
More tweaking of the clipboard monitor with dump/purge
Small tidy of code
Final fixes before the monitor PR
Merge branch 'upstream/master' into clipboard_monitor

Conflicts:
	lib/rex/post/meterpreter/extensions/extapi/tlv.rb
Added binaries from Meterpreter PR #74

Meterpreter PR https://github.com/rapid7/meterpreter/pull/74 was landed,
this adds the binaries from that PR.
Land #2930 - clipboard monitor for meterpreter