comment
improve criteria `extension` method

casecmp was a bug as a substring could match
create a somewhat better fake `pkg` for tests
use `const_get` in container.from_type

instead of iterating over container list
divide Cask::Container::Naked into explicit types

- Cask::Container::Pkg
- Cask::Container::Ttf
- Cask::Container::Otf

which are autodetected based on filetypes as with other
containers.  Cask::Container::Naked remains available
for explicit use in a container_type stanza.
recast `containers` as `autodetect_containers`

and clarify which container types will not autodetect
rename seven_zip.rb to better match class name
doc updated valid values for container_type
Updated owncloud to 1.6.2.551
Tower 2 doesn't have an appcast url right now
Merge pull request #5617 from stonerl/owncloud

Updated owncloud to 1.6.2.551
Update GHC to 7.8.3-r1
Upgrade filezilla to 3.9.0.2

Upgrade filezilla to 3.9.0.2
Merge pull request #5620 from taka-ez/taka-contrib-cask

Upgrade filezilla to 3.9.0.2
Merge pull request #5619 from ndr-qef/ghc

Update GHC to 7.8.3-r1
Merge pull request #5614 from rolandwalker/container_refactor

Refactor Cask::Container, explicit vs autodetected container types
add support for xar containers

references: #5442
Merge pull request #5618 from mAAdhaTTah/tower

Tower 2 doesn't have an appcast url right now
Convert backtick commands to Cask::SystemCommand.run

Closes #4971
Merge pull request #5623 from federicobond/remove-backtick-commands

Convert backtick commands to Cask::SystemCommand.run