implement raw-directory-exists? function in storage package.

This differs from the other file/directory checks because it doesn't create a
directory when it can't find one (usual Common Lisp predicate behaviour with
files/directories).

src/storage.lisp

@@ -29,7 +29,8 @@
            #:copy-storage-directory
            #:copy-raw-directory
            #:get-files-in-raw-directory
-           #:get-raw-subdirectories))
+           #:get-raw-subdirectories
+           #:raw-directory-exists?))
 (in-package #:storage)
 
 (defun init-storage ()
@@ -116,13 +117,15 @@ calling this function."
   "Returns a list of paths for the files in `DIRECTORY-PATH' outside /storage directory."
   (cl-fad:list-directory (make-raw-path directory-path)))
 
+(defun raw-directory-exists? (directory-path)
+  "Checks to see if directory at `DIRECTORY-PATH' (no directory make if none found)."
+  (cl-fad:directory-exists-p (make-raw-path directory-path)))
+
 (defun get-directory-names (directory-names)
   "Returns the final part of a directories absolute path in `DIRECTORY-NAMES'.
 Make sure you use `GET-RAW-DIRECTORIES' to build the `DIRECTORY-NAMES' list."
   (mapcar #'(lambda (x) (first (last (pathname-directory x)))) directory-names))
 
-;; (first (last (pathname-directory (cl-fad:pathname-directory-pathname (first (cl-fad:list-directory (storage:make-raw-path "snapshots/")))))))
-
 (defun make-path (username subdirectory slug)
   "Forms the path used to save a file.
 Storage path: