Multiple fixes:

NEXUS-6836: Bump XStream to fix it on java8
NEXUS-6728: Use updated zapper for preemptive auth
Bumped deps and aligned them
Fix license header

(this is unchanged file in this PR, same is on master )
Merge pull request #15 from sonatype/xstream-zapper-and-updates

Multiple fixes: XStream on Java8, zapper...