Make built-in server actually use the "host" config field

ankisyncd.conf

@@ -1,5 +1,6 @@
 [sync_app]
-host = 127.0.0.1
+# change to 127.0.0.1 if you don't want the server to be accessible from the internet
+host = 0.0.0.0
 port = 27701
 data_root = ./collections
 base_url = /sync/

ankisyncd/sync_app.py

@@ -692,7 +692,7 @@ def main():
     config.read("ankisyncd.conf")
 
     ankiserver = SyncApp(config)
-    httpd = make_server('', config.getint("sync_app", "port"), ankiserver)
+    httpd = make_server(config.get("sync_app", "host"), config.getint("sync_app", "port"), ankiserver)
 
     try:
         print("Serving HTTP on {} port {}...".format(*httpd.server_address))