Generate swagger json (#1402)

- Generate swagger.json into public/
- Add swagger-ui auto-installation
- Add footer link to local swagger-ui
- Add /swagger url for using app url.
- Fix Swagger-UI version via git tag

vendor/code.gitea.io/sdk/gitea/user.go

@@ -10,6 +10,7 @@ import (
 )
 
 // User represents a API user.
+// swagger:response User
 type User struct {
 	ID        int64  `json:"id"`
 	UserName  string `json:"login"`
@@ -18,6 +19,10 @@ type User struct {
 	AvatarURL string `json:"avatar_url"`
 }
 
+// UserList represents a list of API user.
+// swagger:response UserList
+type UserList []*User
+
 // 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