Move tasks/build_object_spec.rb to spec/lib

This commit lays the structure for the tests we will hopefully be setting up
for the packaging repo, and moves the build_object_spec.rb file to
config_spec.rb file, since after the reorg that is what it actually is
testing.

Signed-off-by: Moses Mendoza <moses@puppetlabs.com>
Add more tests for config object, reorg

This commit adds several more tests for Pkg::Config, including a fixtures setup
to handle testing of loading yaml files for configuration data. It elso helps
establish some much needed scaffolding for the tests I hope we add to cover
existing areas that aren't covered, as well as for new functionality.