Implement Configuration Options

[lcreid]

One of the good features of bootstrap_form is that it doesn't require a complicated configuration process before you can use it.

Also, configuration options can greatly increase the development challenge, as you may need test cases for each variation of a configuration option.

On the other hand, there are a lot of good ideas for the future of bootstrap_form that require breaking changes. It would be relatively easy to introduce new features if they could be controlled by an configuration option, so that people who needed the legacy behaviour could retain it easily.

This issue is asking for proposed PRs for a configuration mechanism for bootstrap_form. The mechanism is likely a file in config/initializers, but we're open to other ideas if they have significant benefits.

If you choose to work on this ticket, please write up a brief description of what you plan to do, and assign the issue to yourself (with the "Asignees" like above and to the right).

[sharshenov]

Unfortunately, I don't have sufficient right to assign myself, but here is a draft PR #562 for the requested feature, which also closes #560