Always call request.pushRequestPath/popRequestPath in a try/finally block

Also fix the place where we call the push (before try)
Nexus version 2.6.1 -> 2.7.0
Merge pull request #75 from sonatype/push-pop-in-try-finally

REVIEW: Always call request.pushRequestPath/popRequestPath in a try/finally block
Merge remote-tracking branch 'origin/master' into nexus-5807-prefixes-magic
NEXUS-5807: UTs adjusted, MAGIC added