Initial commit of modules for NTP vulns described in R7-2014-12

Not entirely functional or polished, but mostly working
Gut admin functions from R7-2014-12 NTP modules

None of these are admin modules.  All of that stuff should eventually go
in auxiliary/admin
Return the NTP message, not the string
Add new mixin for helping to detect DRDoS vulns
Update R7-2014-12 NTP modules to use new DRDoS mixin
Move rdoc for Msf::Auxiliary::DRDoS
Add rspec coverage for Msf::Auxiliary::DRDoS
Allow singular NTP version and mode 7 implementation testing
Update ntp_monlist to use UDPScanner, NTP and DRDoS mixins
Only discard monlist replies that are impossibly short

This fixes the case where if a monlist reply only includes one peer
Store peer data note in the same format as originally
If a peer is 127.0.0.1, don't try to store it because we (currently...) can't
Add reference and disclosure date
Land #3696, pile of NTP DRDoS 0days

Dr. DoS in da house?