Fix more warnings

```
spec/dummy/config/boot.rb:4: warning: File.exists? is a deprecated name, use File.exist? instead
lib/omniauth/strategies/radius.rb:26: warning: `*' interpreted as argument prefix
lib/kracken/controllers/json_api_compatible.rb:1: warning: loading in progress, circular require considered harmful - lib/kracken/controllers/json_api_compatible.rb
        from bin/rspec:16:in  `<main>'
        from bin/rspec:16:in  `load'
        from /.gem/ruby/2.2.3/gems/rspec-core-3.4.1/exe/rspec:4:in  `<top (required)>'
        from /.gem/ruby/2.2.3/gems/rspec-core-3.4.1/lib/rspec/core/runner.rb:41:in  `invoke'
        from /.gem/ruby/2.2.3/gems/rspec-core-3.4.1/lib/rspec/core/runner.rb:73:in  `run'
        from /.gem/ruby/2.2.3/gems/rspec-core-3.4.1/lib/rspec/core/runner.rb:88:in  `run'
        from /.gem/ruby/2.2.3/gems/rspec-core-3.4.1/lib/rspec/core/runner.rb:102:in  `setup'
        from /.gem/ruby/2.2.3/gems/rspec-core-3.4.1/lib/rspec/core/configuration.rb:1359:in  `load_spec_files'
        from /.gem/ruby/2.2.3/gems/rspec-core-3.4.1/lib/rspec/core/configuration.rb:1359:in  `each'
        from /.gem/ruby/2.2.3/gems/rspec-core-3.4.1/lib/rspec/core/configuration.rb:1361:in  `block in load_spec_files'
        from /.gem/ruby/2.2.3/gems/rspec-core-3.4.1/lib/rspec/core/configuration.rb:1361:in  `load'
        from spec/kracken/authenticator_spec.rb:1:in  `<top (required)>'
        from spec/kracken/authenticator_spec.rb:1:in  `require'
        from spec/rails_helper.rb:3:in  `<top (required)>'
        from spec/rails_helper.rb:3:in  `require'
        from spec/dummy/config/environment.rb:2:in  `<top (required)>'
        from spec/dummy/config/environment.rb:2:in  `require'
        from spec/dummy/config/application.rb:10:in  `<top (required)>'
        from /.gem/ruby/2.2.3/gems/bundler-1.10.6/lib/bundler.rb:134:in  `require'
        from /.gem/ruby/2.2.3/gems/bundler-1.10.6/lib/bundler/runtime.rb:61:in  `require'
        from /.gem/ruby/2.2.3/gems/bundler-1.10.6/lib/bundler/runtime.rb:61:in  `each'
        from /.gem/ruby/2.2.3/gems/bundler-1.10.6/lib/bundler/runtime.rb:72:in  `block in require'
        from /.gem/ruby/2.2.3/gems/bundler-1.10.6/lib/bundler/runtime.rb:72:in  `each'
        from /.gem/ruby/2.2.3/gems/bundler-1.10.6/lib/bundler/runtime.rb:76:in  `block (2 levels) in require'
        from /.gem/ruby/2.2.3/gems/bundler-1.10.6/lib/bundler/runtime.rb:76:in  `require'
        from lib/kracken.rb:7:in  `<top (required)>'
        from lib/kracken.rb:7:in  `require'
        from lib/kracken/controllers/json_api_compatible.rb:1:in  `<top (required)>'
        from lib/kracken/controllers/json_api_compatible.rb:1:in  `require'
spec/support/omniauth.rb:35: warning: assigned but unused variable - request
```

Author: cupakromer

lib/kracken/controllers/json_api_compatible.rb

@@ -1,5 +1,3 @@
-require 'kracken/controllers/json_api_compatible'
-
 module Kracken
   module Controllers
     module JsonApiCompatible

lib/omniauth/strategies/radius.rb

@@ -23,16 +23,18 @@ def self.provider_url
       uid { raw_info['id'] }
 
       info do
-        raw_info["info"].slice *%w{
-          first_name
-          last_name
-          email
-          uid
-          confirmed
-          teams
-          admin
-          subscription_level
-        }
+        raw_info["info"].slice(
+          *%w{
+            first_name
+            last_name
+            email
+            uid
+            confirmed
+            teams
+            admin
+            subscription_level
+          }
+        )
       end
 
       extra do

spec/dummy/config/boot.rb

@@ -1,5 +1,5 @@
 # Set up gems listed in the Gemfile.
 ENV['BUNDLE_GEMFILE'] ||= File.expand_path('../../../../Gemfile', __FILE__)
 
-require 'bundler/setup' if File.exists?(ENV['BUNDLE_GEMFILE'])
+require 'bundler/setup' if File.exist?(ENV['BUNDLE_GEMFILE'])
 $LOAD_PATH.unshift File.expand_path('../../../../lib', __FILE__)

spec/support/omniauth.rb

@@ -32,7 +32,7 @@ def authenticate_request!(user = OAuthUser)
       get "/auth/radius"
       get response.header['Location']
 
-      request = nil
+      _request = nil
     end
   end
 end