Removed i18n

Since QA Reports is not localized and the only locale file contained
only "hello world" removed the apparently useless dependency.
Updated some of the gems

Updated Nokogiri
Updated Slim
Updated therubyracer
Updated activerecord-import
Removed weird 210px margin from edit dialog

Unclear why this was there but most likely some leftover from earlier
layout. The layout was changed some time ago because it didn't work
anymore.
Catch invalid URI

If user is going directly to a page requiring authentication, e.g.
report editing page, there is no referrer and uri.parse will raise an
exception.