Drop reverse and always require Puppet 4+ style

Puppet 3 is dead and our manifests should be written in the modern
style.

README.md

@@ -38,26 +38,18 @@ gem 'puppet-lint-absolute_classname-check', :require => false
 
 ### Relative class name inclusion
 
-Including a class by a relative name might lead to unexpected results [in Puppet 3](https://docs.puppet.com/puppet/3/lang_namespaces.html#relative-name-lookup-and-incorrect-name-resolution).
+Including a class by a relative name might lead to unexpected results [in Puppet 3](https://docs.puppet.com/puppet/3/lang_namespaces.html#relative-name-lookup-and-incorrect-name-resolution). That's why a lot of manifests explicitly include by the absolute name. Since Puppet 4 names are always absolute and this is no longer needed. This lint check helps to clean up your manifests.
 
 #### What you have done
 
 ```puppet
-include foobar
+include ::foobar
 ```
 
 #### What you should have done
 
 ```puppet
-include ::foobar
-```
-
-#### Reverse this check
-
-This check can be reversed to check for Puppet > 4.
-
-```ruby
-PuppetLint.configuration.absolute_classname_reverse = true
+include foobar
 ```
 
 #### Disabling the check

lib/puppet-lint/plugins/check_absolute_classname.rb

@@ -1,14 +1,8 @@
 PuppetLint.new_check(:relative_classname_inclusion) do
   def check
+    message = 'class included by absolute name (::$class)'
+
     tokens.each_with_index do |token, token_idx|
-      reverse = PuppetLint.configuration.absolute_classname_reverse || false
-      if reverse
-        pattern = '^(?!::)'
-        message = 'class included by absolute name (::$class)'
-      else
-        pattern = '^::'
-        message = 'class included by relative name'
-      end
       if [:NAME,:FUNCTION_NAME].include?(token.type) && ['include','contain','require'].include?(token.value)
         s = token.next_code_token
         next if s.nil?
@@ -22,7 +16,7 @@ def check
               in_function += 1
             elsif in_function > 0 && n && n.type == :RPAREN
               in_function -= 1
-            elsif in_function.zero? && s.value !~ /#{pattern}/
+            elsif in_function.zero? && s.value.start_with?('::')
               notify :warning, {
                 message: message,
                 line: s.line,
@@ -36,7 +30,7 @@ def check
       elsif token.type == :CLASS and token.next_code_token.type == :LBRACE
         s = token.next_code_token
         while s.type != :COLON
-          if (s.type == :NAME || s.type == :SSTRING) && s.value !~ /#{pattern}/
+          if (s.type == :NAME || s.type == :SSTRING) && s.value.start_with?('::')
             notify :warning, {
               message: message,
               line: s.line,
@@ -51,11 +45,6 @@ def check
   end
 
   def fix(problem)
-    reverse = PuppetLint.configuration.absolute_classname_reverse || false
-    problem[:token].value = if reverse
-                              problem[:token].value[2..-1]
-                            else
-                              '::' + problem[:token].value
-                            end
+    problem[:token].value = problem[:token].value[2..-1]
   end
 end