Update DOSBox SVN formula (#4175)

* Update DOSBox SVN formula

The URL for the snapshots has changed (in part because of a policy change by Dropbox). The new URL is a direct link to new builds generated from trunk automatically.

* Remove comment, change to http

* dosbox-svn (latest) Add appropriate URL comment

* update url and comment

* dl.dropboxusercontent.com

Casks/dosbox-svn.rb

@@ -2,8 +2,8 @@ cask 'dosbox-svn' do
   version :latest
   sha256 :no_check
 
-  # dl.dropbox.com/u/7737184 was verified as official when first introduced to the cask
-  url 'http://dl.dropbox.com/u/7737184/Dosbox/Dosbox-Snapshot.dmg'
+  # dl.dropboxusercontent.com/s/kbrf5elbcu66kst was verified as official when first introduced to the cask
+  url 'http://dl.dropboxusercontent.com/s/kbrf5elbcu66kst/Dosbox-Snapshot.dmg'
   name 'DOSBox SVN'
   homepage 'https://www.dosbox.com/wiki/SVN_Builds#Plain.2Fvanilla.2Fclean_SVN_builds/'