Backward compatibility (username vs. login)

Reintroduce the username field for user object on JSON marshal to fix backward
compatibility. Fixes Drone 0.4 compatibility issues.

gitea/user.go

@@ -5,6 +5,7 @@
 package gitea
 
 import (
+	"encoding/json"
 	"fmt"
 )
 
@@ -17,6 +18,16 @@ type User struct {
 	AvatarURL string `json:"avatar_url"`
 }
 
+// MarshalJSON implements the json.Marshaler interface for User, adding field(s) for backward compatibility
+func (u User) MarshalJSON() ([]byte, error) {
+	// Re-declaring User to avoid recursion
+	type shadow User
+	return json.Marshal(struct {
+		shadow
+		CompatUserName string `json:"username"`
+	}{shadow(u), u.UserName})
+}
+
 // GetUserInfo get user info by user's name
 func (c *Client) GetUserInfo(user string) (*User, error) {
 	u := new(User)