I can’t even count the number of rails projects I’ve created over the last five years. For a while I’ve been using the site RailsWizard to take away some of the drudgery of setting up the typical gems I like to work with. Recently someone introduced me to an alternative called Rails Composer.
If you end up on their website it can be difficult to figure out that the functionality they offer is actually free. You can find it, however, if you go to the projects repo page on GitHub. The money line is this:
$ rails new myapp -m https://raw.github.com/RailsApps/rails-composer/master/composer.rb
I suggest you give it a shot. So far it looks really promising to me.