minor cleanup in tar
Namespace all utils

All the utils were defined within Pkg::Util, despite being organized into
separate files. This means it was actually a crapshoot figuring out which file
contained a certain method definition, contrary to standard practices. This
commit drops the utils into modules within Pkg::Util to make this easier. While
costing a bit of verbosity at invocation time, it makes following along a lot
easier.

Signed-off-by: Moses Mendoza <moses@puppetlabs.com>
Add additional comments explaining template in tar.rb
Initial work on rpm