xtrabackup incrementals and apply-logs

[Andrew Garner]

holland 1.0.8+ enables apply-logs by default and attempts to run through innobackupex --apply-logs at the end of a backup. This is automatically disabled if streaming or compression is detected (where we can't trivially apply logs). However, this is also broken in the case of incremental backups - where someone sets --incremental* options in the config's additional-options.

So I suppose we should try to detect this situation by either checking for --incremental there, just as we check for --compress, or perhaps go back to not running apply-logs automatically.