Add first implementation of loading modal

app/corpora/events.py

@@ -55,6 +55,7 @@ def observe_corpus_analysis_connection(app, corpus_id, session_id):
                                      username='opaque')
         analysis_client.connect()
         analysis_clients[session_id] = analysis_client
+        socketio.emit('init_corpus_analysis', 'Ready', room=session_id)
         while session_id in connected_sessions:
             try:
                 analysis_client.ctrl_ping()