Refactor main.py. No longer need to change it if a new plugin is added (except for the command line)

glances/main.py

@@ -367,20 +367,7 @@ Examples of use:
         self.args = args
 
         # Export is only available in standalone or client mode (issue #614)
-        export_tag = (
-            args.export_csv or
-            args.export_cassandra or
-            args.export_couchdb or
-            args.export_elasticsearch or
-            args.export_influxdb or
-            args.export_kafka or
-            args.export_opentsdb or
-            args.export_prometheus or
-            args.export_rabbitmq or
-            args.export_riemann or
-            args.export_statsd or
-            args.export_zeromq
-        )
+        export_tag = any([getattr(args, a) for a in args.__dict__ if a.startswith('export_')])
         if WINDOWS and export_tag:
             # On Windows, export is possible but only in quiet mode
             # See issue #1038