defrag: fix reassembly with vlan

When creating a pseudo packet with the reassembled IP packet, the
parent's vlan id or id's are also needed. The defrag packet is run
through decode and the flow engine, where the vlan id is necessary
for connecting the packet to the correct flow.
vlan: support QinQ ethernet types

Add support for 802.1AD and 802.1QinQ in ethernet and vlan parsing.

Tickets: #814, #1103, #1104
Promote nodes set with --set to sequence nodes as needed.

A node isn't known to be a sequence node until the YAML is parsed.
If a node sequence node was set on the command line, promote
it to a sequence node when it is discovered by YAML to be
a sequence node.

Fixes comment #18 in issue 921.
eve-log: add warning if enabled but not supported

If we're not compiled against libjansson, the eve-log output is not
available. This patch adds a warning.
vlan/QinQ: add vlan_qinq counter

This patch introduces a new counter "decoder.vlan_qinq". It counts
packets that have more than two stacked vlan layers.

Packets with 2 vlan layers will both increment "decoder.vlan" and
"decoder.vlan_qinq".
Update Changelog for 2.0rc1 release