adding warning when timeout is greater than 300

zappa/cli.py

@@ -786,6 +786,9 @@ def update(self):
         # Make sure we're in a venv.
         self.check_venv()
 
+        # Validate settings
+        self.validate_settings()
+
         # Execute the prebuild script
         if self.prebuild_script:
             self.execute_prebuild_script()
@@ -2452,6 +2455,14 @@ def check_venv(self):
                 click.style("Zappa", bold=True) + " requires an " + click.style("active virtual environment", bold=True, fg="red") + "!\n" +
                 "Learn more about virtual environments here: " + click.style("http://docs.python-guide.org/en/latest/dev/virtualenvs/", bold=False, fg="cyan"))
 
+
+    def validate_settings(self):
+        """ Validate settings """
+        # Validate timeout_seconds
+        if self.stage_config.get('timeout_seconds') > 300:
+            click.echo(click.style("Warning!", fg="red", bold=True) + "`timeout_seconds` must be less or equal to 300!"
+
+
     def silence(self):
         """
         Route all stdout to null.