cut v0.18.3 release
a little changelog cleanup
Fix Lion DiskMaker link.
Quassel IRC Client 0.9.1
Add SHA1 to Lion DiskMaker.
Merge pull request #1231 from gillesfabio/fix-lion-disk-maker-version

Fix Lion DiskMaker version and link.
support for nested containers

 - this allows us to support casks for things like "dmg in zip" "zip in
   tar", etc, etc
 - a nested container can be any format that homebrew-cask supports
 - the existing container support is now referred to as a Cask's
   "primary container"
 - use the `nested_container` artifact type to indicate the relative
   path to a nested container that you wanted extracted
 - multiple layers of nesting should work with multiple nested_container
   directives (though this is untested as yet)
 - add SpeedDownload as the first cask to use this feature; refs #602
Merge pull request #1232 from phinze/dev/nested-containers

support for nested containers
cut v0.19.0
work on CONTRIBUTING docs a little
Add new cask for Kobito
Merge pull request #1233 from ksato9700/kobito

Add new cask for Kobito
Electric Sheep 2.7b35b
Update Electric Sheep SHA1