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
Add webview HTTP exploit.
More accurate description.
Fix android detection in os.js.
Add browserautopwn support.
Tweak description.
Tweak checks.
Whitespace tweaks.
Wording tweak.
Msftidy it up.
Add URL for browser exploit.
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
Use BrowserExploitServer mixin.

This prevents drive-by users on other browsers from ever receiving
the exploit contents.