Remove reference to Cask

* README.org: Do it.

Author: nnicandro

README.org

@@ -100,16 +100,9 @@ run some code that creates a widget.
 
 * How do I run the tests?
 
-You must have [[https://github.com/cask/cask][Cask]] installed to be able to run the tests.  Once Cask
-is installed, in the top level directory of this project run the
-following from the command line
-
-#+begin_src shell
-# Install all development dependencies via Cask
-make dev
-#+end_src
-
-Then, to run the tests
+You must have [[https://github.com/doublep/eldev][Eldev]] installed to be able to run the tests.  Once Eldev
+is installed, then in the top level directory of this project you can
+run one of the following from the command line
 
 #+begin_src shell
 # Run the whole set of tests