Add viewport meta tag for mobile devise

refer http://tech.nitoyon.com/ja/blog/2013/02/15/viewport/
Fix AbstractController::DoubleRenderError
Get rid of code in fetch project
Extract comment content in partial layout
Fix comment form design and tweak javascript code
Update gems and start tracking Gemfile.lock
Add validates presence of Comment#body
Merge pull request #78 from kmiyake/iss-77

Add viewport meta tag for mobile devise
Merge pull request #80 from kmiyake/iss-47

Get rid of undesirable code that i think
Merge pull request #81 from kmiyake/iss-76

Fix comment form design and bugfix