Add application name to user-agent header.
Add application name to user-agent header.

The addition of the application name to the user-agent header helps us
better identify and analyize traffic and usage patterns with the
package-router.

Signed-off-by: Ryan Hass <7a1efea0847aa10fda44596a4a622bd3187d968e@users.noreply.github.com>

chef/omnitruck,chef/opscode-omnitruck,chef/omnitruck,chef/opscode-omnitruck,chef/opscode-omnitruck,chef/omnitruck