Resolve all paths to absolute paths

When paths were sent in as relative paths from the CLI, `Exclude`
directives within a rubocop config yml were not correctly applied. This
is because Rubocop internally turns those excludes into absolute paths,
and it seems like it was then trying to match the being-analyzed
relative path against the had-been-made-absolute excluded path.

Author: Will Fleming

lib/cc/engine/file_list_resolver.rb

@@ -29,20 +29,24 @@ def exclude_due_to_config?(path)
       end
 
       def include_based_files_to_inspect
-        @include_paths.map do |path|
-          if path =~ %r{/$}
+        @include_paths.map(&method(:abs_path)).flat_map do |path|
+          if Dir.exist?(path)
             rubocop_runner.send(:find_target_files, [path])
           elsif rubocop_file_to_include?(path)
             path
           end
-        end.flatten.compact
+        end.compact
       end
 
       def local_path(path)
         realpath = Pathname.new(@root).realpath.to_s
         path.gsub(%r{^#{realpath}/}, '')
       end
 
+      def abs_path(path)
+        Pathname.new(path).realpath.to_s
+      end
+
       def rubocop_file_to_include?(file)
         if file =~ /\.rb$/
           true