Merge pull request #418 from sleeplessgeek/paperclip

---

Updated README to make this requirement more noticeable and to explain how to make sure Paperclip has access to its utilities.

README.md

@@ -18,6 +18,21 @@ more detailed options.
 
 The complete [RDoc](http://rdoc.info/gems/paperclip) is online.
 
+Requirements
+------------
+
+ImageMagick must be installed and Paperclip must have access to it. To ensure
+that it does, on your command line, run `which convert` (one of the ImageMagick
+utilities). This will give you the path where that utility is installed. For
+example, it might return `/usr/local/bin/convert`.
+
+Then, in your environment config file, let Paperclip know to look there by adding that 
+directory to its path.
+
+In development mode, you might add this line to `config/environments/development.rb)`:
+
+    Paperclip.options[:command_path] = "/usr/local/bin/"
+
 Installation
 ------------