Again a few V3 to V4 changes (#197)

* Delete deprecated `upvote` and `downvote` fields

* Add http status `Accepted` (202) as successful status

* Rename the milestones field `iid` to `iids` (`[]int`)

gitlab.go

@@ -474,7 +474,7 @@ func (e *ErrorResponse) Error() string {
 // CheckResponse checks the API response for errors, and returns them if present.
 func CheckResponse(r *http.Response) error {
 	switch r.StatusCode {
-	case http.StatusOK, http.StatusCreated, http.StatusNoContent, http.StatusNotModified:
+	case 200, 201, 202, 204, 304:
 		return nil
 	}
 

milestones.go

@@ -58,7 +58,7 @@ func (m Milestone) String() string {
 // https://gitlab.com/gitlab-org/gitlab-ce/blob/8-16-stable/doc/api/milestones.md#list-project-milestones
 type ListMilestonesOptions struct {
 	ListOptions
-	IID *int `url:"iid,omitempty" json:"iid,omitempty"`
+	IIDs []int `url:"iids,omitempty" json:"iids,omitempty"`
 }
 
 // ListMilestones returns a list of project milestones.

notes.go

@@ -47,6 +47,7 @@ type Note struct {
 		State     string     `json:"state"`
 		CreatedAt *time.Time `json:"created_at"`
 	} `json:"author"`
+	System    bool       `json:"system"`
 	ExpiresAt *time.Time `json:"expires_at"`
 	UpdatedAt *time.Time `json:"updated_at"`
 	CreatedAt *time.Time `json:"created_at"`