rename silver/charcoal to gray

lib/philomena/users/user.ex

@@ -605,7 +605,7 @@ defmodule Philomena.Users.User do
     do: user.otp_backup_codes |> Enum.reject(&Password.verify_pass(token, &1))
 
   def theme_colors do
-    ~W(red orange yellow blue green purple cyan pink silver)
+    ~W(red orange yellow blue green purple cyan pink gray)
   end
 
   def theme_names do

lib/philomena_web/views/setting_view.ex

@@ -11,10 +11,7 @@ defmodule PhilomenaWeb.SettingView do
 
   def theme_colors do
     Enum.map(User.theme_colors(), fn name ->
-      case name do
-        "silver" -> {"Silver/Charcoal", name}
-        _ -> {String.capitalize(name), name}
-      end
+      {String.capitalize(name), name}
     end)
   end