More configuration options on Uptime Checks

We gave uptime checks an overhaul with even more configuration options. In addition to the existing settings, you can now:

• Specify the HTTP method (GET, POST, etc.)
• Add custom request headers
• Specify the expected status code with conditions like < and =

All existing uptime checks are configured using GET, no custom headers, and with an expected status code less than 400. The options can be found by expanding the new Request and Response groups when creating/editing an uptime check.