Delay 5 minutes the clean up process after an app pool recycle

Delay 5 minutes the clean up process after an APP Pool recycle.
This commit includes a fix when the daysBeforeRemoveExpired parameter (web.config) value is 0 or negative. It happened once and I guess it was due to an error reading the web.config file. The problem is that in this case the parameter is set to its default value 0, what means files will be deleted all the time.