Fix some CRAN policy issues

Change-Id: I6862ea1bfbadbaf5d6090b6655c21ecf66650c16
diff --git a/DESCRIPTION b/DESCRIPTION
index 9a8238e..d0982a8 100644
--- a/DESCRIPTION
+++ b/DESCRIPTION
@@ -56,7 +56,10 @@
     knitr,
     purrrlyr,
     raster,
-    tidyverse
+    tidyverse,
+    sf,
+    geojsonsf,
+    viridisLite
 Collate: 
     'logging.R'
     'KorAPConnection.R'