Disable Gravatar (#37)

* Disable Gravatar
* Lowercase emails
* Add migration

fs_embed.go

@@ -4,5 +4,5 @@ package main
 
 import "embed"
 
-//go:embed templates/*/*.html public/manifest.json public/assets/*.js public/assets/*.css public/assets/*.svg
+//go:embed templates/*/*.html public/manifest.json public/assets/*.js public/assets/*.css public/assets/*.svg public/assets/*.png
 var dirFS embed.FS