bin/console requires Pry in production

[mpmenne]

First, thank you for the great gem!

When I added the wannabe_bool gem to my project, I noticed that I was unable to access the Rails console in production. After digging in, it appeared that my project was falling back to the bin/console in the wannabe_bool gem.

Of course, I could always add my own bin/console in my project, but I thought it would be nice to remove the dependency on Pry in production in the gem itself.

I've created #15 to address the issue. It was a bit tricky to test, so just the changes. Please let me know if you have any feedback.

[prodis]

@mpmenne Thank you for raising this issue. I have just review the PR #15.