Support for uncached data loading

So you don't have to restart the server, you can add "cache_data": false option to config.json to not cache data.
Documented in CONFIG.md
I added a require_module function that either does or does not cache the data based on this configuration option.

Signed-off-by: deadvey <deadvey@deadvey.com>

example-config.json

@@ -5,6 +5,7 @@
     "site_url": "https://example.com",
     "language": "en-US",
     "port": 8080,
+    "cache_data": false,
     "allow_signup": true,
     "site_description": "Read my blogs!",
     "timeline_length": 20,