Remove read constraint for directories on key path

On Unix, do not check whether all directories on the path to storage_dir
are readable; in corporate environments this is often not the case.

Closes #28.

src/enchive.c

@@ -369,15 +369,8 @@ storage_directory(char *file)
     s = strchr(path + 1, '/');
     while (s) {
         *s = 0;
-        if (dir_exists(path) || !mkdir(path, 0700)) {
-            DIR *dir = opendir(path);
-            if (dir)
-                closedir(dir);
-            else
-                fatal("opendir(%s) -- %s", path, strerror(errno));
-        } else {
+        if (mkdir(path, 0700) && !dir_exists(path))
             fatal("mkdir(%s) -- %s", path, strerror(errno));
-        }
         *s = '/';
         s = strchr(s + 1, '/');
     }