Bug fixes, changes to packet_modifier
* src/core/util.py
  -- Added a function to resolve a hostname to an IP
* src/modules/poison/dns.py
  -- Removed a stray newline
  -- Modified it so that hostnames are automatically resolved to IPs
* src/modules/services/telnet.py
  -- Remoed a stray newline
* src/modules/sniffer/packet_modifier.py
  -- Still under development, but bugs were fixed
  -- Added a hooking method to allow other modules to plug-in
  and modify packets
  -- Added packet dropping functionality, so other modules may drop
  packets at the kernel level if they so choose