Replace Rails guide (for new app setup) with guide to setting up an exis...

[daguar]

...ting app, closes #27

[daguar]

@migurski — As someone not from the Ruby ecosystem, want to see if this makes sense to you. If so, wanna merge?

[migurski]

Almost! It’s a big improvement. I’d remove the git clone part, it’s simultaneously too general and too specific. Does the part about project-specific versions of Ruby get adequately covered in Ruby.md? Will people definitely have bundle available after getting RVM?

[daguar]

I’d remove the git clone part

Done, on the branch.

Does the part about project-specific versions of Ruby get adequately covered in Ruby.md?

I don't think it was adequately covered in there, but I do think the Ruby howto is the right place for Ruby version stuff, so I've migrated some of the additional RVM context I gave over there, and deleted it from the Rails howto.

Will people definitely have bundle available after getting RVM?

I am 99.9% sure the answer is yes. On RVM's install page ( https://rvm.io/rvm/install ) it has a section on "To install without rubygems-bundler and rvm gems..." that says to provide explicit override arguments to avoid installing bundler. I also followed the Ruby/RVM howto recently on @bsmithgall's comp, and it came with bundler.