Add BoardConfiguration API

Why?
Allow for lookup of configuration information for a specific board.

See JIRA API documentation:
https://developer.atlassian.com/cloud/jira/software/rest/#api-rest-agile-1-0-board-boardId-configuration-get

Completes sumoheavy#316

lib/jira-ruby.rb

@@ -38,6 +38,7 @@
 require 'jira/resource/webhook'
 require 'jira/resource/agile'
 require 'jira/resource/board'
+require 'jira/resource/board_configuration'
 
 require 'jira/request_client'
 require 'jira/oauth_client'

lib/jira/client.rb

@@ -159,6 +159,10 @@ def Board
       JIRA::Resource::BoardFactory.new(self)
     end
 
+    def BoardConfiguration
+      JIRA::Resource::BoardConfigurationFactory.new(self)
+    end
+
     def RapidView
       JIRA::Resource::RapidViewFactory.new(self)
     end

lib/jira/resource/board.rb

@@ -46,6 +46,13 @@ def issues(params = {})
         results.map { |issue| client.Issue.build(issue) }
       end
 
+      def configuration(params = {})
+        path = path_base(client) + "/board/#{id}/configuration"
+        response = client.get(url_with_query_params(path, params))
+        json = self.class.parse_json(response.body)
+        client.BoardConfiguration.build(json)
+      end
+
       # options
       #   - state ~ future, active, closed, you can define multiple states separated by commas, e.g. state=active,closed
       #   - maxResults ~ default: 50 (JIRA API), 1000 (this library)

lib/jira/resource/board_configuration.rb

@@ -0,0 +1,9 @@
+module JIRA
+  module Resource
+    class BoardConfigurationFactory < JIRA::BaseFactory # :nodoc:
+    end
+
+    class BoardConfiguration < JIRA::Base
+    end
+  end
+end