Use extracted download strategy.

Formula/jython.rb

@@ -1,19 +1,12 @@
 require 'formula'
 
-# even though "file -b" reports this as a zip archive, it's just a binary
-class JythonHttpDownloadStrategy <CurlDownloadStrategy
-  def stage
-    FileUtils.mv @dl, File.basename(@url)
-  end
-end
-
 class Jython <Formula
   url 'http://downloads.sourceforge.net/project/jython/jython/2.5.1/jython_installer-2.5.1.jar'
   homepage 'http://www.jython.org'
   md5 '2ee978eff4306b23753b3fe9d7af5b37'
 
   def download_strategy
-    JythonHttpDownloadStrategy
+    NoUnzipCurlDownloadStrategy # Don't unzip jar.
   end
 
   def install

Formula/sbt.rb

@@ -1,12 +1,5 @@
 require 'formula'
 
-# even though "file -b" reports this as a zip archive, it's just a binary
-class SbtHttpDownloadStrategy <CurlDownloadStrategy
-  def stage
-    FileUtils.mv @dl, File.basename(@url)
-  end
-end
-
 class Sbt <Formula
   JAR = 'sbt-launcher-0.5.5.jar'
   url "http://simple-build-tool.googlecode.com/files/#{JAR}"
@@ -14,7 +7,7 @@ class Sbt <Formula
   md5 'e3593448b3be17ce1666c6241b8d2f90'
 
   def download_strategy
-    SbtHttpDownloadStrategy
+    NoUnzipCurlDownloadStrategy # Don't unzip jar.
   end
 
   def install