Remove credentials file (#229)

* Remove credentials file

This removes the credentials.yml.enc file and generates the
secret_key_base randomly on each application boot.

* SECRET_KEY_BASE should be passed as env var

This key is used to generate stable/authenticated activestorage URL's
which we want to be stable in order to have optimal caching.

README.md

@@ -36,8 +36,14 @@ you want.
     * DATABASE_URL
     * RACK_ENV
     * RAILS_ENV
-  Optionally set the following variables to control where Accentor
-  stores its files:
+    * SECRET_KEY_BASE
+
+    You can generate a new `SECRET_KEY_BASE` using `bin/rails secret`.
+    For optimal caching, this key should be stable.
+
+    Optionally set the following variables to control where Accentor
+    stores its files:
+
     * FFMPEG_LOG_LOCATION
     * RAILS_STORAGE_PATH
     * FFMPEG_VERSION_LOCATION

config/environments/production.rb

@@ -18,7 +18,7 @@
 
   # Ensures that a master key has been made available in either ENV["RAILS_MASTER_KEY"]
   # or in config/master.key. This key is used to decrypt credentials (and other encrypted files).
-  config.require_master_key = true
+  config.require_master_key = false
 
   # Disable serving static files from the `/public` folder by default since
   # Apache or NGINX already handles this.