chore: Clean up Gemfile and specification

Gemfile

@@ -1,10 +1,3 @@
-ENV['rails'] ||= ENV['orm'] == "mongoid4" ? '4.0.2' : '3.2.13'
-
 source 'https://rubygems.org'
 
-# Define Rails version
-gem 'rails', ENV['rails']
-
-gem 'doorkeeper'
-
 gemspec

doorkeeper-openid_connect.gemspec

@@ -12,16 +12,16 @@ Gem::Specification.new do |spec|
   spec.description   = %q{OpenID Connect extension to Doorkeeper.}
   spec.license       = %q{MIT}
 
-  spec.files         = `git ls-files -z`.split("\x0")
-  spec.executables   = spec.files.grep(%r{^bin/}) { |f| File.basename(f) }
-  spec.test_files    = spec.files.grep(%r{^(test|spec|features)/})
+  spec.files         = `git ls-files -z`.split("\x0").reject do |f|
+    f.match(%r{^(test|spec|features)/})
+  end
+  spec.executables   = spec.files.grep(%r{^exe/}) { |f| File.basename(f) }
   spec.require_paths = ['lib']
 
-  spec.add_dependency 'railties', '>= 3.1'
-  spec.add_dependency 'doorkeeper', '>= 1.3'
-  spec.add_dependency 'sandal', '~> 0.6.0'
+  spec.add_runtime_dependency 'doorkeeper', '~> 4.0'
+  spec.add_runtime_dependency 'sandal', '~> 0.6'
 
-  spec.add_development_dependency 'rspec-rails', '~> 2.99.0'
-  spec.add_development_dependency 'generator_spec', '~> 0.9.0'
-  spec.add_development_dependency 'factory_girl', '~> 2.6.4'
+  spec.add_development_dependency 'rspec-rails'
+  spec.add_development_dependency 'rails'
+  spec.add_development_dependency 'sqlite3'
 end

lib/doorkeeper/openid_connect.rb

@@ -11,6 +11,8 @@
 
 require 'doorkeeper/openid_connect/rails/routes'
 
+require 'doorkeeper'
+
 module Doorkeeper
   module OpenidConnect
     def self.configured?