BUG-1770: emit proper namespaces

We add calls to setPrefix() and only use the calls with explicit
namespace prefix to emit elements.

Change-Id: Ib603567b3080388c6016ece5e34cac6a723ef8c0
Signed-off-by: Robert Varga <rovarga@cisco.com>
Merge "BUG-1770: emit proper namespaces"