refactor nera: call string-is-nil-or-empty? from validation package.

This is part of a multi-part commit to port the string-is-nil-or-empty? function
from the utils package to the validation package. The code has a lot of
'utils:string-is-nil-or-empty?' dotted around so this took a few commits to
port. There is a chance I've missed it in some obsure places so don't be
surprised if you see a future commit relaying something similar to this one.

src/nera.lisp

@@ -6,6 +6,7 @@
 	#:hermetic
 	#:ritherdon-archive.db
 	#:utils
+        #:validation
 	#:user
 	#:pages
 	#:files
@@ -142,9 +143,9 @@
   (with-connection (db)
     (let ((user-to-update
 	    (mito:find-dao 'user:user :username username)))
-      (if (not (utils:string-is-nil-or-empty? display-name))
+      (if (not (validation:string-is-nil-or-empty? display-name))
 	  (setf (user::display-name-of user-to-update) display-name))
-      (if (not (utils:string-is-nil-or-empty? new-password))
+      (if (not (validation:string-is-nil-or-empty? new-password))
 	  (setf (user::password-of user-to-update) (hermetic::hash new-password)))
       (mito:save-dao user-to-update))))
 
@@ -196,9 +197,9 @@ editted article entry as the first item in the list.."
   "Add a new `PAGE' to the database."
   (with-connection (db)
     (let ((page-to-update (mito:find-dao 'page :id id)))
-      (if (not (utils:string-is-nil-or-empty? title))
+      (if (not (validation:string-is-nil-or-empty? title))
 	  (setf (pages::title-of page-to-update) title))
-      (if (not (utils:string-is-nil-or-empty? slug))
+      (if (not (validation:string-is-nil-or-empty? slug))
 	  (setf (pages::slug-of page-to-update) slug))
       (if (not (null nav-menu))
 	  (setf (pages::enable-nav-menu-p page-to-update) nav-menu))

src/utils.lisp

@@ -7,7 +7,6 @@
 	#:app-constants
 	#:storage)
   (:export #:request-params
-	   #:string-is-nil-or-empty?
 	   #:separate-files-in-web-request
 	   #:set-alert
 	   #:get-alert