Update bower to 1.7.4
Update bower to 1.7.4

qnyp/heroku-buildpack-ruby-bower,moneyadviceservice/heroku-buildpack-ruby-bowndler,zoomer/heroku-buildpack-ruby-bower,zoomer/heroku-buildpack-ruby-bower,qnyp/heroku-buildpack-ruby-bower,moneyadviceservice/heroku-buildpack-ruby-bowndler