Make sure UTC is always used internally (#713)

* force app timezone to be UTC

* remove asDateTime overwrite

* add custom column to display dates in user timezone

* use `APP_TIMEZONE` as default timezone for new users

* revert accidental pinting

config/app.php

@@ -7,6 +7,8 @@ return [
 
     'version' => 'canary',
 
+    'timezone' => 'UTC',
+
     'exceptions' => [
         'report_all' => env('APP_REPORT_ALL_EXCEPTIONS', false),
     ],