Add deprecation util for the sprintf and vsprintf functions

README.markdown

@@ -530,11 +530,9 @@ words("   ")
 
 #### sprintf(string format, ...arguments) => string
 
-C like string formatting.
-Credits goes to [Alexandru Marasteanu][o].
-For more detailed documentation, see the [original page][o].
+C like string formatting. Makes use of the [sprintf-js](https://npmjs.org/package/sprintf-js) package.
 
-[o]: http://www.diveintojavascript.com/projects/javascript-sprintf
+**This function will be removed in the next major release, use the [sprintf-js](https://npmjs.org/package/sprintf-js) package instead.**
 
 ```javascript
 sprintf("%.1f", 1.17);

package.json

@@ -61,6 +61,7 @@
     }
   },
   "dependencies": {
-    "sprintf-js": "^1.0.3"
+    "sprintf-js": "^1.0.3",
+    "util-deprecate": "^1.0.2"
   }
 }

sprintf.js

@@ -1 +1,4 @@
-module.exports = require('sprintf-js').sprintf;
+var deprecate = require('util-deprecate');
+
+module.exports = deprecate(require('sprintf-js').sprintf,
+  'sprintf() will be removed the next major release, use the sprintf-js package instead.');

vsprintf.js

@@ -1 +1,4 @@
-module.exports = require('sprintf-js').vsprintf;
+var deprecate = require('util-deprecate');
+
+module.exports = deprecate(require('sprintf-js').vsprintf,
+  'vsprintf() will be removed the next major release, use the sprintf-js package instead.');