Gemfile, .rspec and Yarn updates

[malachaifrazier]

1. Several Gem version updates
2. Updated .rspec to display more info
3. upgraded Yarn
4. Updated .ruby-version to use 2.2.5

[brunofacca]

Thanks for your contribution :)

If you don't mind, I'd like to know more about a few of your choices.

Any specific reason for leaving both pg and mysql2 uncommented in the Gemfile?

Why Ruby 2.2.5 in .ruby-version? I think specifying a Ruby version is a good idea, but then we should probably use the latest stable version (2.4.2). What do you think?

Why list Ruby 2.5 as a dependency in README.md? The current stable version is 2.4.2.

Why modify schema.rb?

Thanks again.

[malachaifrazier]

Whoopsie. The pg and mysql gems being uncommented was an oversight on my part.
You're absolutely correct about the ruby version...by bad.
The schema modification happened automatically when I bundle install, so we can consider it trivial?

Fixing all the things now.