add new plugin nhk_program_info.rb
Fix a missing 'return` for API Error..
Display credit as item by API rule.
remove support of iddy.jp because the service EOL

* see: http://iddy.jp/blog/log/2014/02/000089.php
* replace Iddy class to dummy
* fallback to twitter when :iddy specified as service
Merge pull request #80 from tdiary/remove_iddy

remove support of iddy.jp because the service EOL