Bump Rails to 4.1.8

See
http://weblog.rubyonrails.org/2014/11/17/Rails-3-2-21-4-0-12-and-4-1-8-have-been-released/.
Merge pull request #120 from yous/patch-gem

Bump Rails to 4.1.8
implement LessEditor for read posts
Merge branch 'feature/read_post' into develop
Fix RuboCop offenses
Rename TermHelper to Helper to follow file name