Integrate support for more files into processing and upload

The restriction that only pdf files can be uploaded is removed. All
files can now be uploaded. The processing may not process all. It is
still possible to restrict file uploads by types via a configuration.

modules/webapp/src/main/elm/Comp/Dropzone.elm

@@ -35,7 +35,7 @@ type alias Settings =
 defaultSettings : Settings
 defaultSettings =
     { classList = \_ -> [ ( "ui placeholder segment", True ) ]
-    , contentTypes = [ "application/pdf" ]
+    , contentTypes = []
     }
 
 
@@ -148,7 +148,11 @@ filterMime settings files =
         pred f =
             List.member (File.mime f) settings.contentTypes
     in
-    List.filter pred files
+    if settings.contentTypes == [] then
+        files
+
+    else
+        List.filter pred files
 
 
 dropDecoder : D.Decoder Msg