The Gemfile.lock file should exist only for applications and not for
libraries.

The Gemfile was also pointing at a specific version that is no longer
there (current git is at 1.3.1) so there is little gain on keeping it
that way.

The current code seems to work fine with modern uuidtools and modern
libxml-ruby so there is no reason to artificially limit the version to
very old ones.

This actually allows tests to be run from systems such as Gentoo, by
setting up enough variables during execution.