Update docker util script and travis to use new base container

util/docker_build.sh

@@ -46,5 +46,5 @@ fi
 dir=$(pwd -W 2>/dev/null) || dir=$PWD  # Use Windows path if on Windows
 
 # Run container and build firmware
-docker run --rm -it $usb_args -v "$dir":/qmk_firmware qmkfm/qmk_firmware \
+docker run --rm -it $usb_args -w /qmk_firmware/ -v "$dir":/qmk_firmware qmkfm/base_container \
 	make "$keyboard${keymap:+:$keymap}${target:+:$target}"