implement restore-from-snapshot function in snapshot package.

src/snapshot.lisp

@@ -29,8 +29,10 @@ user can repopulate that database after they have restored this website. The
 
 (defun restore-from-snapshot (snapshot-name)
   "Deletes the data in /storage and the DB and replaces it with `SNAPSHOT-NAME'."
-  (format t "RESTORE-FROM-SNAPSHOT NOT IMPLEMENTED."))
+  (storage:remove-raw-directory "storage/")
-
+  (storage:remove-raw-directory "db/")
+  (storage:copy-raw-directory (format nil "snapshots/~a/storage/" snapshot-name) "storage/")
+  (storage:copy-raw-directory (format nil "snapshots/~a/db/" snapshot-name) "db/"))
 
 (defun delete-snapshot (snapshot-name)
   "Deletes the snapshot in the /snapshots directory with `SNAPSHOT-NAME'."