Bumped ruby patch-level in .ruby-version.
Removed activesupport gem and timecop gem.

We do not use them anywhere.
Use sinatra-assetpack and serve css from less files.

There is no need to rebuild css files with prepare.sh script.
Serve js via sinatra-asset-pack.
Removed unused js, css and imgs.
Removed Login button from navbar.
Unified style for mailchimp form.