Fix the user add email

src/mail_templates/user_added.ejs

@@ -1,6 +1,6 @@
 <%if (format === 'text') { %>
 
-Dear Admin,
+Hi <%= cloudronName %> Admin,
 
 User with email <%= user.alternateEmail || user.email %> was added to your <%= cloudronName %> Cloudron.
 

src/mail_templates/welcome_user.ejs

@@ -15,7 +15,7 @@ Your <%= invitor.email %>
 
 <center>
 
-<img src="<%= cloudronAvatarUrl %>"/>
+<img src="<%= cloudronAvatarUrl %>" width="128px" height="128px"/>
 
 <h3>Hi <%= user.displayName || user.username || user.alternateEmail || user.email %>,</h3>