Change Network Topology panel so it stops polling ajax on error

Change javascript so that we don't use interval that will always call
AJAX, instead only schedule next AJAX poll when we have successfully
finished the previous AJAX request.
This avoids many calls with errors if token times out.

Fixes bug #1253768

Change-Id: I74c4bf8cb931655ce64783ae11467183275386ab
Live migration support

Currently Horizon only provides support for 'nova migrate', which
involves a reboot, and is also confusing for users who do not know there
are 2 ways of migrating an instance. We should provide another option in
order to support live migration, as enabled by `nova live-migration`.

Implements blueprint live-migration-support

Change-Id: Id83ba9e19461a7217f521a09bde3109428ecbf11
Merge "Live migration support"
Merge "Change Network Topology panel so it stops polling ajax on error"