Fix Atom/RSS feed parsing due to changes in jteeuwen/go-pkg-xmlx.

Due to recent changes involving how values are dealt with in xmlx, update
the RSS/Atom parsing.  Instead of using the Value property of an xmlx Node,
use the new GetValue function offered in PR jteeuwen/go-pkg-xmlx#15.
Add travis configuration file.

Add travis configuration information, to automatically test my version.