Add a task to check for updates periodically

It must be enabled and configured by the admin.

Refs: #990

modules/common/src/main/scala/docspell/common/config/Implicits.scala

@@ -21,6 +21,9 @@ import scodec.bits.ByteVector
 
 object Implicits {
 
+  implicit val accountIdReader: ConfigReader[AccountId] =
+    ConfigReader[String].emap(reason(AccountId.parse))
+
   implicit val pathReader: ConfigReader[Path] =
     ConfigReader[JPath].map(Path.fromNioPath)