Fix rails helpers

hi!

Small fix to 'evil-front' core: move helpers initializer from 'evil-front-rails' to core gem.

Why not 'evil-front-rails'? Because it has to much deps, some of them incompatible (e.g. 'jquery-cdn', I'm working  with 'jquery-rails-cdn' (goddamned ie8)) or unnecessary (e.g. evil-blocks).