Allow float value when overriding downtime

Live migration downtime is configured as an integer option while
a default value is set to a float number. When a user tries to
override the option with another float number he receives a ValueError.
This patch changes the option to allow overriding with a float
number.

Change-Id: I955f4ec09c9a2fbaed61a82839ac15d3eef29ab0
1 file changed