Add a new request package in integration-cli

The goal is to remove function from `docker_utils.go` and setup
simple, one-responsability package that can be well tested ; and to
ease writing request.

This moves all the calls to `sockRequest` (and similar methods) to
their counterpart in the `request` package.

This introduce `request.Do` to write easier request (with functional
argument to easily augment the request) with some pre-defined function
for the most used http method (i.e. `request.Get`, `request.Post` and
`request.Delete`).

Few of the `sockRequest` call have been moved to `request.Do` (and
`Get`, etc.) to showcase the usage of the package. There is still a
whole lot to do.

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

integration-cli/docker_api_inspect_test.go

@@ -8,6 +8,7 @@ import (
 	"github.com/docker/docker/api/types"
 	"github.com/docker/docker/api/types/versions/v1p20"
 	"github.com/docker/docker/integration-cli/checker"
+	"github.com/docker/docker/integration-cli/request"
 	"github.com/docker/docker/pkg/stringutils"
 	"github.com/go-check/check"
 )
@@ -107,7 +108,7 @@ func (s *DockerSuite) TestInspectAPIImageResponse(c *check.C) {
 	dockerCmd(c, "tag", "busybox:latest", "busybox:mytag")
 
 	endpoint := "/images/busybox/json"
-	status, body, err := sockRequest("GET", endpoint, nil)
+	status, body, err := request.SockRequest("GET", endpoint, nil, daemonHost())
 
 	c.Assert(err, checker.IsNil)
 	c.Assert(status, checker.Equals, http.StatusOK)