Increased timeout for Heat autoscaling test
Increased timeout for Heat autoscaling test

The autoscaling timeout in Ceilometer is 600 seconds,
we need to make sure autoscaling will make an alarm
in Ceilometer withing timeout*2 + several seconds to
pass this test in 100% of cases.

Change-Id: I6b2a43e4acb4b8d76641ee314ca19e67b999500a
Closes-Bug: #1584190

stackforge/fuel-ostf,stackforge/fuel-ostf