Test failure:
```
Failure/Error:
expect(described_class.search_taps("some-formula"))
.to match(formulae: ["homebrew/foo/some-formula"], casks: ["homebrew/bar/some-cask"])
GitHub::API asked to yield |[{"items"=>[{"path"=>"Formula/some-formula.rb", "repository"=>{"full_name"=>"Homebrew/homebrew-foo"}}, {"path"=>"Casks/some-cask.rb", "repository"=>{"full_name"=>"Homebrew/homebrew-bar"}}]}]| but no block was passed
```
- Instead use class methods.
- This is better than use it as a mixin
when only a small number of methods are
used in each class or module.
- It also allows us to conditionally
require it in `brew install`.
- Removed unused search require in descriptions.rb.
