Documentation Updates

[Tim Soderstrom]

I've gone through and fleshed out a few parts of the wiki and figured I would just let people know about that. Specifically, I started working on documentation for the mysqldump provider, adding in docs for mysqldump + LVM and fleshed out the Backup Sets Explained page to include the new backup-set retention policy changes (which I have also updated some of the configs with). I also updated our Backup-Set diagram to include the new backup sets and throw out some of the old ones.

If anyone finds anything glaring, let me know!