install: don't search when formula is unreadable.

audit: allow skipping audit methods.

create: use GitHub metadata where available.

These formulae are detected as missing but exist in an unreadable form.

Fixes #2485

GitHub provides a description and homepage field so let `brew create`
use them where possible. Also, detect GitHub repositories based on
`releases` as well as `archive`s.

Add `--only` and `--except` methods which can be used to selectively
enable or disable audit groups.

audit: check for more universal usage.

uses: allow checking deleted formulae.

install: do not search taps when a qualified formula is missing

This is useful for seeing when formulae are deleted if they are going to
leave behind any formulae that depend on them.

As a result, if there are any formulae returned return a non-zero/failed
exit status.

travis.yml: keep taps.

audit: deprecate language module requirements.

This will avoid `brew doctor` trying to retap `homebrew/core` which is
both slow and error-prone.

Hardware cpu can run arch helper

[WIP] Added test for check_access_lock_dir

audit: don't recommend version aliases on --devel.

Fix `brew cask audit` not working without argument.

xcode: 8.3.1 is latest version.

As requested in #11462 by @neutric as this produces confusing,
incorrect output.

missing_formula: fix undefined method `path` for nil:NilClass

formulary: Workaround for method missing for downcase on Pathname object

Make `brew audit` complain about language module requirements because
they provide a crappy user experience compared to vendoring and we’re
not really fixing bugs in them any more.

Also check for `ENV.universal_binary` and `build.universal?`. The prior
is still required for `wine` and the latter should never be required any
longer.

This check for a nil `tap` is necessary because Tap.from_path(path)
will simply return a nil value in the event the tap path is invalid

Our CI images are already updated with it.

gpg_spec test add 2.1.x compatibility

Virtualenv relocation fixes