Adding make target for building with a full source map

Makefile

@@ -185,8 +185,15 @@ run-client:
 
 	cd $(BUILD_WEBAPP_DIR) && $(MAKE) run
 
+run-client-fullmap:
+	@echo Running mattermost client for development with FULL SOURCE MAP
+
+	cd $(BUILD_WEBAPP_DIR) && $(MAKE) run-fullmap
+
 run: run-server run-client
 
+run-fullmap: run-server run-client-fullmap
+
 stop-server:
 	@echo Stopping mattermost