Add default api base

uptimestatus/__init__.py

@@ -1,9 +1,13 @@
 #!/usr/bin/env python3
 
 from flask import Flask
+import os
 
 app = Flask(__name__)
 
-app.config.from_envvar('UPTIMESTATUS_SETTINGS')
+app.config["PROMETHEUS_API_BASE"] = "http://[::1]:9090"
+
+if "UPTIMESTATUS_SETTINGS" in os.environ:
+    app.config.from_envvar('UPTIMESTATUS_SETTINGS')
 
 from .views import app