Don't validate an option in ejabberd_config:get_option() functions

The commit introduces the following changes:
* Now there is no need to pass validating function in
  ejabberd_config:get_option() functions, because the configuration
  keeps already validated values.
* New function ejabberd_config:get_option/1 is introduced
* Function ejabberd_config:get_option/3 is deprecated. If the function
  is still called, the second argument (validating function) is simply
  ignored.
* The second argument for ejabberd_config:get_option/2 is now
  a default value, not a validating function.

src/rest.erl

@@ -37,12 +37,7 @@
 
 start(Host) ->
     p1_http:start(),
-    Pool_size =
-	ejabberd_config:get_option({ext_api_http_pool_size, Host},
-				   fun(X) when is_integer(X), X > 0->
-					   X
-				   end,
-				   100),
+    Pool_size = ejabberd_config:get_option({ext_api_http_pool_size, Host}, 100),
     p1_http:set_pool_size(Pool_size).
 
 stop(_Host) ->
@@ -167,9 +162,6 @@ base_url(Server, Path) ->
         <<"http", _Url/binary>> -> Tail;
         _ ->
             Base = ejabberd_config:get_option({ext_api_url, Server},
-                                              fun(X) ->
-						      iolist_to_binary(X)
-					      end,
                                               <<"http://localhost/api">>),
             <<Base/binary, "/", Tail/binary>>
     end.