Make mirror-gem Ruby 2.0 compatible

This adds checks before making Gem::SpecFinder calls to prevent errors while
using Ruby 2.0. Gem::SpecFetcher#fetch_with_errors has been replaced by
Gem::SpecFetcher#spec_for_dependency. Additionally, #spec_for_dependency
returns a Gem::Source object where #fetch_with_errors returned a String.
Merge pull request #76 from alexkonradi/fix_mirror-gem_ruby_2.0_compatibility

Make mirror-gem Ruby 2.0 compatible
Merge pull request #77 from alexkonradi/add-import-deb-packages

Add ability to import deb packages while building the image
Support multiple .deb package source URLs

The official Debian packages are already broken up into "main", "contrib", and
"non-free" groups, which means that there is no single source of even
'official' packages. This patch adds support for using multiple package lists
in place of a single one.

Note: the order in which lists are specified DOES MATTER. If the same package
is available in multiple repositories, the repository listed first will take
precedence.
Make bin/deb2tcz.sh more robust

This fixes some variable name confusion in deb2tcz.sh and improves the handling
of more complicated packages (those with startup scripts).
Merge pull request #79 from alexkonradi/enhancement/multiple-deb-package-sources

Extend .deb package importing to support multiple sources
Merge branch 'master' of github.com:tjmcs/PL-Razor-Microkernel into tb/add-jruby-to-razor