Removing puma dependency

Is there any specific reason to add puma as dependency?

I am using puma in my staging and production servers, but for development I prefer webrick, cause it is single thread. Whether gems puma or mina-puma (before this PR) are included in Gemfile when I run `rails s`, puma is started as app server (dev env). I removed both gems and webrick returned as default. So I tested removing puma from Gemfile and removing puma as dependency in mina-puma, then I still can make deploys (mina env deploy) and the tasks from mina-puma still are running ok (`mina puma:stop`, `mina puma:start`..). Why we need puma as a dependecy?