Add generic section icon in section picker + clean up legacy section icon stuff

src/Umbraco.Web/Models/ContentEditing/Section.cs

@@ -11,9 +11,6 @@ namespace Umbraco.Web.Models.ContentEditing
         [DataMember(Name = "name")]
         public string Name { get; set; }
 
-        [DataMember(Name = "cssclass")]
-        public string Icon { get; set; }
-
         [DataMember(Name = "alias")]
         public string Alias { get; set; }
 

src/Umbraco.Web/Models/Mapping/SectionMapperProfile.cs

@@ -12,7 +12,6 @@ namespace Umbraco.Web.Models.Mapping
         {
             CreateMap<ISection, Section>()
                 .ForMember(dest => dest.RoutePath, opt => opt.Ignore())
-                .ForMember(dest => dest.Icon, opt => opt.Ignore())
                 .ForMember(dest => dest.Name, opt => opt.MapFrom(src => textService.Localize("sections/" + src.Alias, (IDictionary<string, string>)null)))
                 .ReverseMap(); //backwards too!
         }