Add zero-config self hosting on Render (#612)

* v1 of backend implementation for self hosting

* Add docs

* Add upgrades controller

* Add global helpers for self hosting mode

* Add self host settings controller

* Conditionally show self hosting settings

* Environment and config updates

* Complete upgrade prompting flow

* Update config for forked repo

* Move configuration of github provider within class

* Add upgrades cron

* Update deploy button

* Update guides

* Fix render deployer

* Typo

* Enable auto upgrades

* Fix cron

* Make upgrade modes more clear and consistent

* Trigger new available version

* Fix logic for displaying upgrade prompts

* Finish implementation

* Fix regression

* Trigger new version

* Add i18n translations

* trigger new version

* reduce caching time for testing

* Decrease cache for testing

* trigger upgrade

* trigger upgrade

* Only trigger deploy once

* trigger upgrade

* If target is commit, always upgrade if any upgrade is available

* trigger upgrade

* trigger upgrade

* Test release

* Change back to maybe repo for defaults

* Fix lint errors

* Clearer naming

* Fix relative link

* Add abs path

* Relative link

* Update docs

test/controllers/registrations_controller_test.rb

@@ -25,7 +25,7 @@ class RegistrationsControllerTest < ActionDispatch::IntegrationTest
   end
 
   test "create when hosted requires an invite code" do
-    in_hosted_app do
+    in_invited_app do
       assert_no_difference "User.count" do
         post registration_url, params: { user: {
           email: "john@example.com",
@@ -54,10 +54,10 @@ class RegistrationsControllerTest < ActionDispatch::IntegrationTest
 
   private
 
-  def in_hosted_app
-    ENV["HOSTED"] = "true"
+  def in_invited_app
+    ENV["REQUIRE_INVITE_CODE"] = "true"
     yield
   ensure
-    ENV["HOSTED"] = nil
+    ENV["REQUIRE_INVITE_CODE"] = nil
   end
 end