add binary in Skim.app Cask

Skim has three shared command line tools, displayline, skimnotes and
skimpdf. Other applications may need these binaries to interact with
Skim, for features like TeX-PDF Synchronization etc.
Update to version 0.3.0

Kitematic has just released a new version that solves some problems for people on Yosemite. https://github.com/kitematic/kitematic/issues/99#issuecomment-59678616
demote the Tap migration banner in FAQ.md
hide error outputs from plutil
Add Bowery version 3.2.7
Update virtualhostx.rb
Add Stepmania.app v5beta4
Merge pull request #6858 from vinkla/bowery

Add Bowery version 3.2.7
Rename e-tax-2014.rb to e-tax2014.rb
Edit Cocktail cask in order to use conditionals
Merge pull request #6860 from paracycle/patch-1

Update Kitematic.app to v0.3.0
Merge pull request #6867 from fza/master

Edit Cocktail cask in order to use conditionals
Merge pull request #6861 from yipeipei/fix-skim-binary

add binary in Skim.app Cask
basic docs for stub gpg stanza
Merge pull request #6866 from jordannoble/stepmania

Add Stepmania.app v5beta4a
convert adobe-air.rb to use `installer :script`

* remove `caskroom_only true`
* remove `postflight`
convert amazon-music.rb to use `installer :script`

* remove `caskroom_only true`
* remove `postflight`
use `installer :script` in private-internet-access

* hoist primary command out of `postflight` into `installer` artifact
* this Cask did not use the `caskroom_only` idiom
use installer :manual in adobe-creative-cloud
use installer :manual in backblaze