Change Rails and rspec dependency

[Issue #6] https://github.com/skinnyworm/wechat-rails/issues/6
Fix rspec errors

[Issue #6] https://github.com/skinnyworm/wechat-rails/issues/6
Fix deprecated method of rspec

[Issue #6] https://github.com/skinnyworm/wechat-rails/issues/6
Update dummy application to Rails 4.0

[Issue #6] https://github.com/skinnyworm/wechat-rails/issues/6
Undergrade rspec matcher falsey and truthy

[Issue #6] https://github.com/skinnyworm/wechat-rails/issues/6
Merge pull request #7 from fahchen/master

Add rails4 support
since rails4 remore xml_parse, add post_xml to get post xml

..
Merge remote-tracking branch 'github/0.1.2'
modify responder, change block scope within controller action, allow use of controller helper and instant method
Merge pull request #15 from lazing/master

make responder execute in action context, fixes rails 4.0 compitable issue