Serialized data borked on edit

Hi Pippin,

Thanks for the plugin, this helped me sort out some issues I’ve been having with transients on a client site.

Unfortunately, I wasn’t able to resolve them in the plugin. I had to edit the expiration of a transient (which coincidentally could be better labeled on the edit screen) and I found that updating the “Expires in” field would bork the serialized data stored in the “value” field, rendering the transient busted.