Remove smb message struct

It is encapsulated in SMBMessage.
Along with this we don't need the test cases for verifying SMB structure sizes -
we don't rely on packing to make sure the serialization is occurring correct, so
the tests are meaningless now.
Set up parser to parse both SMB and SMB2
Parse SMB response header
Parse SMB negotiate response
Fix compile error checking loose throw specifiers
Fix command comparison in parser

The type was being read incorrectly and examining too many bytes
Add an empty handler for SMB negotiate