(PUP-736) Remove description from RPM/DPKG

Encoding mis-match causes package prefetching to fail with
'invalid byte sequence in US-ASCII'. The guidelines for the
Debian Project [1] and the Fedora Project [2] specify that
metadata files should be UTF-8 encoded, but it is not
enforced.

Since we are not able to force encoding "UTF-8" to work around
this we have decided to back out the description from package
formats for now while working on a longer term solution for
encoding.

Without this fix the package formats fail if there is a package
with UTF-8 encoding in the description.

[1]: http://www.debian.org/doc/debian-policy/ch-controlfields.html
[2]: http://fedoraproject.org/wiki/Packaging:Guidelines#Encoding

Paired with Josh Partlow <joshua.partlow@puppetlabs.com>
(PUP-736) Do not test for package not found

And log unmatched lines at debug level. The executors for dpkg and rpm
will raise an error if the command line returns a non-zero status, which
it does for package not found errors.  This bypasses parsing and is
interpretted as package absent result.  Therefore there is no need to
attempt to parse 'package not found' and we can avoid any issues with
changing or translated messages.

If there are unrecognizable lines of output returned from a successful
execution, log them at debug level.  Logging at a warning level has the
potential to produce too much noise.

Dpkg#query is no longer multi-line output and no longer requires
filtering through a pipe.
Merge pull request #2233 from jpartlow/issue/stable/pup-736-remove-rpm-dpkg-description-fetching

Issue/stable/pup 736 remove rpm dpkg description fetching