Add a Gemfile and travis file for testing the packaging repo

We're going to be testing the packaging tools more thoroughly than we currently
are, which means we should be testing in travis for its easiness and
awesomeness. However, to ensure we have rake and rspec ready in the testing
environment, we need a Gemfile for bundler.

Yes, I said it. Bundler. Alright, bundler. You won.

Signed-off-by: Moses Mendoza <moses@puppetlabs.com>
Merge pull request #264 from MosesMendoza/maint/master/travis

Add a travis file for testing the packaging repo
(maint) Add untar_into method

This commit adds a simple method that shells out to tar to unpack a tarball
into a target directory. Basic sanity checks are present, but this assumes a
tar that can gunzip and untar at once.
(maint) Add fetch_uri method to Pkg::Util::Net

This commit adds a simple utility method to fetch and download a uri to a
location on disk. It is pure ruby and as such is more portable than curl or
wget.