Percona XtraBackup FreeBSD port updated to the version 2.1.3

Version 2.1.3 adds some new functionality (including encryption) and also supports MySQL 5.6. Also, to support decompression of the compressed archives I decided to add qpress archiver to the ports tree. See http://www.freshports.org/databases/xtrabackup/ for the details. Please also make a note, that new versions support only MySQL 5.1 (with InnoDB plugin only), MySQL 5.5 and MySQL 5.6.