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>

script/test-integration

@@ -3,6 +3,8 @@
 export SCRIPTDIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
 export DEST=.
 
-TESTFLAGS="$TESTFLAGS"
-#godep go test -v ./integration
+TESTFLAGS="$TESTFLAGS -test.timeout=30m -check.v"
+
+cd integration
+GOPATH=`godep path`:$GOPATH go test $TESTFLAGS