Add countdown timer to homepage
Remove public/dist from .gitignore

This directory will be vcs'ed until a better way to deploy to heroku is
found.
Improve layout

* add snow
* make good-looking-guy image mobile
* add red color
* add /48 to number of sold türchen (e.g. 9/48)
Add -webkit-transform directive and alias $
Add actionmailer to Gemfile
Add welcome mail to each new imp

Mails are sent using ActionMailer and postmark on production.
Fix postmark settings in order to work correctly

The sender address must be a valid address and configured in the postmark
backend.
Only protect POST new imp
Add link to imps and hide form for non authed users