[ANN] SMB plugin for packetgen v0.5.0

* home: <https://github.com/sdaubert/packetgen-plugin-smb>
* bugs: <https://github.com/sdaubert/packetgen-plugin-smb/issues>

packetgen-plugin-smb 0.5.0 is out.

packetgen-plugin-smb adds support for SMB protocol suites to PacketGen.

PacketGen provides simple ways to generate, send and capture network
packets.

Changes:

### 0.5.0 / 2018-10-18

* Add support for Link-Local Multicast Name Resolution (LLMNR).
* Add support for SMBv1 Negotiate command.
* Add SMB#parse? and SMB2#parse?.
* Add SMB2::Negotiate::Context#calc_length and #record_from_hash
* Fixes:
** SMB2: set response flag to 1 when adding a response header
** SMB2::Negotiate::Request/Response#calc_length: padding is not set,
and now calls #calc_length on each context in #context_list.
** SMB2::SessionSetup::Request/Response#calc_length: now set #buffer_offset.
** GSSAPI now supports olf windows versiobn (mech_list_mic is ANY
instead of OCTET STRING).
** Add GSSAPI#to_s to let it serialize to send packet.