`Hardware.is_32_bit?` is deprecated.

Fixes https://github.com/Homebrew/homebrew-core/issues/3973.

- ignore Cask's files in `readall` (for now, there's an intentional
  syntax error that will need fixed)
- run Cask's tests if they exist
- don't check Cask's files in coverage reports (for now)

This option does more than just print warnings so let's make a more
generic description with a more specific example.

Closes #716.

- Inconsistent or unneeded indentation
- Missing or superfluous empty lines
- Missing or wrongly formatted arguments in command summary
- Missing punctuation

Closes #694.

Add a new `Sandbox.formula?` method to see if a given formula should be
sandboxed. Use the formula to check its tap against a list of
pre-approved taps where we know every formula builds under the sandbox
(currently just homebrew/core).

Simplify checking if we’re going to sandbox a test with `Sandbox.test?`.

Test that sandbox does not complain about bogus .pyc errors and does
complain about other failures.

Closes #684.

These are never fatal and often confusing.

Fixes #683.

Loosen this a bit; we don't necessarily expect the end commit is the one
we're looking for, just that it has changed from the start commit (i.e.
some sort of update has occurred).

Addresses some false negatives on `master` branch merges that weren't
present on the PR commits.

And arguments can be passed through to it.

Tweak produced out of conversation in
https://github.com/Homebrew/brew-evolution/pull/8.

versions should be initialized even if formula is not installed

`test-bot --ci-testing` supports a `--tap` option for non-core taps, so
`brew pull` should too when pulling Homebrew Testing jobs.

Swats away this annoying warning when the test is skipped due to GPG being
unavailable:

```
  1) Skipped:
GpgTest#test_create_test_key:
GPG Unavailable

Error:
GpgTest#test_create_test_key:
NoMethodError: undefined method `rmtree' for nil:NilClass
    /usr/local/Library/Homebrew/test/test_gpg.rb:11:in `teardown'
```

Closes #675.

Signed-off-by: Dominyk Tiller <dominyktiller@gmail.com>

Removes the detection logic from the Requirement in favour of it living inside
the Gpg class & us calling it from there. It's a bit nicer & avoids us calling
Requirement code from outside of direct requirement handling & fulfillment.