Private Email Service Support (#1028)

* Added ServerSettingKey's for SMTP and moved email service code to Kavita. Nothing integrated in the UI yet.

* Undo all the custom SMTP stuff and prepare for custom email service url.

* Foundation for email service to use a custom url is setup.

* Implemented the ability to hook up custom email url

API/Helpers/AutoMapperProfiles.cs

@@ -2,6 +2,7 @@
 using System.Linq;
 using API.DTOs;
 using API.DTOs.CollectionTags;
+using API.DTOs.Email;
 using API.DTOs.Metadata;
 using API.DTOs.Reader;
 using API.DTOs.ReadingLists;
@@ -148,7 +149,6 @@ namespace API.Helpers
 
             CreateMap<IEnumerable<ServerSetting>, ServerSettingDto>()
                 .ConvertUsing<ServerSettingConverter>();
-
         }
     }
 }