Updated Travis builds for nRF52840 to use version 3.0 of the nRF5 SDK for Thread and Zigbee.
Updated Travis builds for nRF52840 to use version 3.0 of the nRF5 SDK
for Thread and Zigbee.

openweave/openweave-core,openweave/openweave-core,openweave/openweave-core,openweave/openweave-core,openweave/openweave-core,openweave/openweave-core