cross GM migration support
GL receive the migration request (fill in the proper GM)
send then to the source GM
Migration is performed by source GM (like in reconfiguration)
Source GM send update request to the destination GM (if needed) 
and start monitoring to the dest localcontroller

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Change monitoring.external to external.notifier.
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GMid were unfilled during submission process.
Now fixed.

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sed monitoring.external / external.notifier