Adds an addressed hex dump function to Rex::Text

Builds on to_hex_dump to add an address column

Useful when working with railgun:

mem = client.railgun.memread(address, 16)
puts Rex::Text.to_addr_hex_dump(mem, address)

004c3638    04 00 00 00 64 00 00 00 b8 f3 00 78 36 4c 00    ....d.....K.x6L.

(Spacing displays better in msfconsole!)

(Converted some space to tab to stop msftidy complaining also)