PowerShell connector operation timeout

Add a feature to allow a timeout to be specified for a PowerShell connector operation (Import All, etc).  When the timeout expires, forcibly kill the PowerShell operation and log an error.

This came up because a connector hung for ten days in a UNIFYConnect environment until I noticed.  All of the other connectors in the same connector exclusion group were blocked from running as well.  I suggest a default timeout of one hour for most operations and 10 minutes for Import Changes.