Switch to security 3.1-SNAPSHOT
Changes to compile with security 3.1-SNAPSHOT
Changes to work with security 3.1-SNAPSHOT

Changes to work with thread-safety changes made in security 3.1
Update kenai to use security 3.1-SNAPSHOT

Also remove duplicate entry for security-xml-realm dep
Merge remote-tracking branch 'origin/master' into security-concurrency
Merge pull request #850 from sonatype/security-concurrency

REVIEW: Switch to security 3.1-SNAPSHOT