Defer :script uninstall, add :early_script

fixes #2254
indent to two spaces

This patch contains only whitespace changes, plus a short
addition to CONTRIBUTING.md on the project-wide indent style
rename audiobook-binder.rb to audiobookbinder.rb
according to rules given in CONTRIBUTING.md
Numerous additions to "brew cask doctor"

New versions, paths, environment variables, and tests.
Side effect: release version must be stored in two locations.
add dependencies for Homebrew Formulae

new DSL key `depends_on_formula`
add dev script list_loaded_kext_ids

For the benefit of Cask authors writing uninstall stanzas
add dev script list_running_app_ids

to help Cask authors with uninstall :quit
`brew cask home` with no args opens project page

- in duplication of similar functionality in Homebrew
- in celebration of proposed design by @ndr-qef
Merge pull request #2546 from rolandwalker/indenting

indent to two spaces
search docs/test/fix tapname-search

This is the promised followup to #2496
- docs
- test
- bugfix: search string was being tested against fully-qualified
  Cask name including Tap, so "brew cask search phinze" would
  (confusingly) return all Casks.
Add a cask for Trailer.app.

 * Install version 1.0.7
Update Light Table to 0.6.2
Merge pull request #2577 from ndr-qef/light-table

Update Light Table to 0.6.2
Update plex-home-theater to v1.0.9.180.
Merge pull request #2578 from darrenli/plex-home-theater

Update plex-home-theater to v1.0.9.180.
Merge pull request #2552 from rolandwalker/audiobookbinder_rename

rename audiobook-binder.rb to audiobookbinder.rb
Merge pull request #2559 from tadejm/trailer-app

Add a cask for Trailer.app.
CONTRIBUTING: Add method for finding package ids.

Package IDs are contained within <pkg-info> tags within PackageInfo
files. These files can be located by unpackaging a package with
`pkgutil --expand` and then using the `find` command.
Merge pull request #2526 from goxberry/how-to-find-package-id

CONTRIBUTING: Add method for finding package ids.
doc error: vagrant uninstall incorrect