:github source uses `git://` url by default, `https://` is recommended.
See http://bundler.io/v1.15/guides/git.html#security

We do the same in our `Gemfile` and templates.

This reverts commit 3420a145, reversing
changes made to afb66a5a.

5.1.0 has been released, and the gem templates can reflect that now.

The current code base is not uniform. After some discussion,
we have chosen to go with double quotes by default.

The bug report templates are now executed from the `ci/travis.rb` when
`GEM` contains `guides`.

I started by creating a `test` task in `guides/Rakefile` to handle this,
but since inline `gemfile` must not be executed with `bundle exec`, that
rake task would not be consistent with others. So I went back by
executing them directly from `Build`.

Use inline Gemfile dependency when reporting gem bugs

This template gives contributors a starting point to use when reporting bugs
that does not involve Active Record or Action Pack.