Enable a require that matches Gem name's hyphen

[tbehling]

This PR enables the RubyTerraform gem to be required by its gem name, which uses a hyphen, ruby-terraform. Currently, the library can only be required by its underscored name, ruby_terraform, which does not match its gem name.

When using RubyTerraform in a Ruby on Rails app, I found the library was not being auto-loaded, despite being in the Gemfile. Unless the app explicitly included a require "ruby_terraform", it would throw the exception uninitialized constant RubyTerraform (NameError). After chasing this through several rabbit holes, I realized that Rails' invocation of Bundler expects the convention that a gem can be required by its gem name.

The issue can be illustrated by this excerpt from a Rails console:

[1] pry(main)> Bundler.require(*Rails.groups)
=> [Gem::Dependency.new("aws-sdk-ec2", Gem::Requirement.new(["~> 1"]), :runtime),
---&<---
 Gem::Dependency.new("ruby-terraform", Gem::Requirement.new(["~> 0.56.0"]), :runtime)]

[2] pry(main)> RubyTerraform
NameError: uninitialized constant RubyTerraform

[3] pry(main)> require 'ruby-terraform'
LoadError: cannot load such file -- ruby-terraform

[4] pry(main)> require 'ruby_terraform'
=> true
[5] pry(main)> 

This PR is a small patch to make both names work, with the hyphen and underscore. This allows Rails to auto-load the gem, with its hyphen, while not breaking backward compatibility with code that requires the gem using the underscore name.

Incidentally, Rubygems does have another gem called ruby_terraform, with the underscore. It appears that one is from 2016, with no further updates, and pre-dates the earliest version of this gem.

[tobyclemson]

Thanks for this.

[tobyclemson]

Version 0.60 includes this change.