Merge pull request #8 from beomjae/master

포스트에 이미지 첨부기능 추가가
add posts_count to User
add locale config path to config/application.rb
add image upload folder to gitignore
add tag to  posts
add simple_form initializer for boostrap style file input
Merge pull request #9 from junheon/master

Counter cache 추가, 댓글 기능 추가, Bootstrap style form file input
Update README.md