Fix missing dep on circle

Signed-off-by: Olivier Gambier <olivier@docker.com>

circle.yml

@@ -9,6 +9,7 @@ machine:
 
   post:
     - gvm install go1.5 -B --name=stable
+    - gvm use stable && go get github.com/mitchellh/gox
 
   environment:
   # Convenient shortcuts to "common" locations

test/integration/run-bats.sh

@@ -7,7 +7,7 @@ set -e
 
 function build_machine() {
     cd ${MACHINE_ROOT}
-    ./script/build
+    make build-x
     cd -
 }
 
@@ -27,7 +27,7 @@ function cleanup_machines() {
 }
 
 function machine() {
-    "$MACHINE_ROOT"/"$MACHINE_BIN_NAME" "$@"
+    "$MACHINE_ROOT"/bin/"$MACHINE_BIN_NAME" "$@"
 }
 
 function run_bats() {
@@ -68,7 +68,7 @@ EXIT_STATUS=0
 export BATS_FILE="$1"
 
 # build machine binary if needed
-if [ ! -e "$MACHINE_ROOT"/"$MACHINE_BIN_NAME" ]; then
+if [ ! -e "$MACHINE_ROOT"/bin/"$MACHINE_BIN_NAME" ]; then
     build_machine
 fi