Added class-id-name to avatar form

resolves ExpressionEngine/ExpressionEngine#2689

Author: robinsowell

docs/member/edit-avatar.md

@@ -20,11 +20,28 @@ This tag allows users to edit their avatar image. The image will be uploaded to
 
 ## Parameters
 
+### `form_class=`
+
+    form_class="login"
+
+This parameter allows you to specify the class attribute for the <form> tag.
+
+### `form_id=`
+
+    form_id="login"
+
+This parameter allows you to specify the id attribute for the <form> tag.
+
+### `form_name=`
+
+    form_name="login"
+
+This parameter allows you to specify a name attribute for the <form> tag.
+
 ### `return=`
 
     return="member/profile"
 
-
 ## Form Inputs
 
 ### `userfile`