[WIP] Rails 4 upgrade

**DO NOT MERGE YET, WORK IN PROGRESS!**

To get some first feedback I'm already creating this pull request. Of course we will cleanup the commits when it's done for merging.

There will me multiple barclamp pull requests linked against this pull request.
I think this string `t(".export.#{bc}")` goes against the goal of having each barclamp allow to plug some export functionality. The string should instead live in the namespace of the barclamp in question, imho.