Introduce GPG operations

Add methods for cryptographic authentication of Cask packages with
the GPG software suite.

Homebrew Cask invokes the system-standard `gpg` binary to import
keys to the GPG keychain, download signatures to versioned metadata
folders, and verify packages. Homebrew Cask aborts if any step fails.

GPG verification is not currently invoked during the audit or
installation processes, and is intentionally left undocumented.

Example usage:
    gpg = Cask::GpgCheck.new(cask)
    gpg.verify(package_archive_path) if gpg.available
revise accessibility methods in postflight miniDSL

* rename `remove_accessibility_access` to `disable_accessibility_access`
  to match corresponding method `enable_accessibility_access`
* move `TCC.db` and `.AccessibilityAPIEnabled` paths to `Cask::Locations`
* remove unneeded backslash from `TCC.db` path
* use full paths to `touch` and `sqlite3` utilities
* use `@command.run` instead of `system_command` which is intended as an
  external interface
* reverse conditional so enable/disable logic is consistent
* `sudo` is needed when creating `.AccessibilityAPIEnabled`
* instead of silent fail, warn that access cannot be safely disabled on
  Mountain Lion and earlier (it could, but might affect other apps)
* quoting/whitespace
revise plist methods in postflight mini-DSL

* accept index argument to `info_plist` in case of multiple `app`
  artifacts, defaulting to first
* return `Pathname` object from `info_plist`
* use `@command.run` instead of `system_command` which is intended
  as an external interface
* quoting
revise move_to_app method in postflight mini-DSL

* use `@command.run` instead of `system_command` which is intended
  as an external interface
* quoting
remove DSL-change banner
Add eclipse-cpp.
Merge pull request #7694 from weijianwen/eclipse-cpp

Add eclipse-cpp.
Upgrade Hive to v1.4.1
Upgrade Cloud Foundry CLI to 6.7.0
Merge pull request #7709 from cunnie/cloudfoundry-cli

Upgrade Cloud Foundry CLI to 6.7.0
Merge pull request #7708 from deizel/hive

Upgrade Hive to v1.4.1
Update vagrant-manager to v2.1.2

Update vagrant-manager to v2.1.2

Upgrade vagrant-manager to version 2.1.2. Latest version release 9th November 2014
Add zap stanza for doubleTwist
Merge pull request #7712 from jawshooah/zap-doubletwist

Add zap stanza for doubleTwist
Merge pull request #7698 from rolandwalker/remove_dsl_banner

remove DSL-change banner
Upgrade Slack to 1.0.2
Update bitmessage to 0.4.4
Merge pull request #7706 from retbrown/vagrant-manager

Update vagrant-manager to v2.1.2
Merge pull request #7714 from askielboe/update-bitmessage-0.4.4

Update bitmessage to 0.4.4
Merge pull request #7713 from srushe/upgrade-slack-to_v1_0_2

Upgrade Slack to 1.0.2