Suppor conditional output if BubbleWrap is installed

This is a backwards compatible and non-breaking change that does the following:

1. Detects if the user is using the `BubbleWrap` gem.
2. If not, it does the same thing it has always done.
3. If so, it checks to see if `BW.debug` is set to true.
4. If not, the the `ap` call will not output anything.
5. If so, it will allow the console output to proceed as normal.

This is based on my blog post: http://blog.markrickert.me/leaving-debug-code-in-production-apps and I figured that making it automatic would be useful.

I hope you merge this and release a new gem version! I know a few people that have been pestering me to implement this functionality in this gem.

cc/ @GantMan