Added two new commands and two config.yml flags

Hi there; I've added some resources to this plugin that I needed to manage my own server, and believe they might be useful to others; two commands:

/resetclaims <player> -- resets a player's accrued blocks and deletes their existing claims; essentially the player "begins again" as if they had just joined the server

/setblockbank <player> <#> -- sets the player's accrued blocks to the specified amount; this can be more useful than using the bonus blocks command when the change needs to be explicit to the accrued blocks for one reason or another.

...and two flags in config.yml:

DrainLiquidsOnAbandon: <True|False> -- when false, the current GriefPrevention behavior of liquids being drained on a claim abandonment or deletion does not occur.

TrackSignChanges: <True|False> -- when false, the current GriefPrevention behavior of notifying moderators/admins on sign placement and changes will not occur; useful when this behavior is tracked by another plugin or it is desired that this behavior not be tracked.

Thank you,
--MKindy
on BukkitDev as LordMarcus