Catalyst::Plugin::Static::Simple: Add ETag support

This should keep browsers from caching Hydra's static files for too
long.
Update rubygems
Add bitbucket-backup rubygem
Making vimprobable2 use the default nixos ca bundle by default
surf: updating to 0.6

it didn't work since the libsoup update, and now it doesn't work either.
Let's see after fixing libsoup.
Test::WWW::Mechanize::Catalyst: Update to 0.58
Revert "libsoup: Update to 2.40.3"

For some reason, the update to 2.40.3 seems to cause troubles for
surf and vimprobable2.

This reverts commit 9642adef3222a2cf9f883b97b7c5de6e172ca50b.
Add chromedriver: a server for running Selenium tests in Chrome
Catalyst::Plugin::Static::Simple: Always send the Expires header

Otherwise Firefox will get confused.
nijs: Added nodejs package