dcache-xrootd: Extend and improve xrootd access log plugin

Adds more information to the access log plugin output, and refines the existing
output.

Target: trunk
Require-notes: yes
Require-book: no
Acked-by: Karsten Schwank <karsten.schwank@desy.de>
Patch: https://rb.dcache.org/r/7470/
Request: 2.11
Request: 2.10
(cherry picked from commit cb1b475805fe3ba90aad9a7328a88fec1b26134e)
Fix compilation for Java 7

Target: 2.11
Patch: none
Merge pull request #1036 from gbehrmann/fix/2.11/rb7470

dcache-xrootd: Extend and improve xrootd access log plugin