This reverts commit 3e4547f5, reversing
changes made to 6edf9382.

This reverts commit 23728729, reversing
changes made to 3e4547f5.

This reverts commit 8d948e4b, reversing
changes made to 23728729.

Tweak our Travis CI configuration and the one we suggest for taps to
be faster and use caching.

If people have `HOMEBREW_RUBY_PATH` set then things explode in a rather
confusing fashion. Instead, run `bundle` for them with the arguments
that they'd want.

Also, move `macho` requires into the module itself; it's a pain having
to do everything for Bundler before requiring `pathname` which is a core
Ruby class.

Homebrew's actually ended up using a fair few gems. While we want to
avoid Bundler at runtime (and this PR still does that, in fact uses
Bundler even less at runtime than it did before) writing our own version
to use at build-time seems redundant.

Extra command_args in gain_permissions_remove caused silent failure and path never gets deleted.

This passed a symbol to `:except_cops` which caused a .

This avoids an error when RuboCop installed installed yet.

CC @GauthamGoli FYI.

Also, don't delete them after that. This means that `brew postinstall`
becomes a way to easily reinstall configuration files for any formula
without needing any changes to any bottles or requiring a reinstall.

It may not exist before Gem installation which means that the resulting
installed gem will not be found in the PATH.

Also refactor audit cops into two "departments"
 - FormulaAudit
 - FormulaAuditStrict

Current:
```
This formula is keg-only, which means it was not symlinked into /usr/local.

Qt has CMake issues when linked
```

After:
```
This formula is keg-only, which means it was not symlinked into /usr/local,
because Qt has CMake issues when linked.
```