[ticket/11103] Move all email templates to the email/ directory & prep short

Prepare short email templates (to be used in jabber)

PHPBB3-11103

phpBB/language/en/email/short/post_disapproved.txt

@@ -0,0 +1,12 @@
+Subject: Post disapproved - "{POST_SUBJECT}"
+
+Hello {USERNAME},
+
+You are receiving this notification because your post "{POST_SUBJECT}" at "{SITENAME}" was disapproved by a moderator or administrator.
+
+The following reason was given for the disapproval:
+
+{REASON}
+
+
+{EMAIL_SIG}