Add post-exploitation module to get FW filtering rules
Ports default values added, is_internal REX function added, reference added
Do minor cleanup
Merge pull request #6 from jvazquez-r7/review_4187

Do minor cosmetic cleanup for post-exploitation module to get FW filtering rules
session.tunnel_peer changed by session.session_host. Other minor changes
Rex::Socket.to_sockaddr changed
Rex::Socket.to_sockaddr changed
recvfrom allocation changed
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Do minor module clean up
Land #4187, @BorjaMerino's post module to get output rules
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