Defer :script uninstall, add :early_script

fixes #2254
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
add arch_only to caveats mini-DSL

Relevant to points raised by @goxberry in #2581
add architecture to `brew cask doctor`
Support external commands beneath `brew cask`
update new ios7-screensaver Cask
- fix checksum
- convert caveats to do block
- use manual_installer from the caveats DSL to generate standard msg
  with full path
- use undocumented caskroom_only feature to make clear what is going
  on here, pending the addition of screensaver artifact support
can't init a CONSTANT with ||= in Ruby 1.8.x

test suite could only run under Ruby 1.9 or above
CONTRIBUTING: Add method for finding kexts.

Method based on previous experience finding bundle id(s) and
grepping through packages.
Merge pull request #2652 from tazran/master

Add DeathToDSStore.app Cask
Update: Aquamacs 3.0a.

Download URL on Aquamacs homepage is a redirect to GitHub. The
redirect URL was determined via `curl --write-out redirect_url`.
Caveats added to redirect users of 32-bit Intel-based Macs to
caskroom/versions/aquamacs25.
Add caveats to Paraview.
Merge pull request #2656 from goxberry/update-paraview-caveats

Add caveats to Paraview.
carefully unload lanchctl services at uninstall

Fixes #2601
- do a soft test to see if the service is loaded before attempting remove
- test/unload as both superuser and user as the service can be installed
  differently according to the original packags
- add tests for uninstall :launchctl; there were none previously
Merge pull request #2596 from rolandwalker/ios7_ss_caveats

update new ios7-screensaver Cask
add Reporting Bugs section to README
Add Paragon ExtFS

Simple variation of Paragon NTFS
Added Nmap 6.40-2

This package also installs the Zenmap GUI.
Merge pull request #2660 from chazlarson/paragon-extfs

Add Paragon ExtFS