Time to remove Xerces/Xalan dep from V3 POMs?

[Cantor, Scott]

I believe we've had prior discussions about intending to eliminate the
requirement to endorse those jars and start supporting JAXP out of the box
in the next version, but we haven't made the changes yet in the POMs. I
think we should start testing and developing that way sooner rather than
later.

I may not know exactly what to change yet, there's a lot of stuff in the
POMs on this, but I know we need to eliminate the endorsement step from
the Maven release profile, and get rid of the specific references to
Xerces/Xalan.

I'm not sure if we need to explicitly reference the JAXP APIs the way we
do for JSON and other things, since we're targeting Java 7 only, but I
think we probably might want to to baseline the JAXP version we're
depending on.

There's an issue open for this but mostly empty and without any detail but
I can fill that in if we're ready to pull the trigger on this.

-- Scott