Merge upstream v2018.06

[tsyesika]

These are the commits in v2018.06 upstream.

[takikawa]

Benchmarking notes for this: tested on snabb1, following the process for #1105

• [x] 1 instance, 2 NIC interfaces -- (9.999 pretty consistently)
• [x] 1 instance, 2 NIC interfaces (from configuration file) (generally 9.999, got a 9.374 once)
• [x] 1 instance, 1 NIC interface (on-a-stick mode) -- (9.999)
• [x] 1 instance, 1 NIC interface (on-a-stick mode, from configuration file) -- (9.999)
• [x] 2 instances, 2 NIC interfaces (from configuration file) -- (high variability, ranged from 8.564, 7.3 to 9.3, 9.16)
• [x] 2 instances, 1 NIC interface (on-a-stick mode, from configuration file) -- (9.999)
• [x] 1 instance, 1 NIC, 2 queues -- (9.999)