Update build toolchain to the use of docker…

… for integration tests.

- Update circle.yml to start the docker daemon listening on TCP (to be
  able to talk to it from the container running test-integration)
- Update script/test-integration to prepare the use of go-check
- Update Makefile in order to run less "binary" target and setting up
  the right environment variable for the builds

Signed-off-by: Vincent Demeester <vincent@sbr.pm>

circle.yml

@@ -1,11 +1,15 @@
 machine:
-  services:
-    - docker
+  pre:
+    - sudo docker -d -e lxc -s btrfs -H tcp://0.0.0.0:2375:
+        background: true
+    - sleep 5
   environment:
     REPO: $CIRCLE_PROJECT_USERNAME/$CIRCLE_PROJECT_REPONAME
+    DOCKER_HOST: tcp://172.17.42.1:2375
 
 dependencies:
   pre:
+    - docker version
     - go get github.com/tcnksm/ghr
     - make validate
   override:
@@ -13,8 +17,10 @@ dependencies:
 
 test:
   override:
-    - make test
+    - make test-unit
+    - make MAKE_DOCKER_HOST=$DOCKER_HOST test-integration
   post:
+    - make crossbinary
     - make image
 
 deployment: