Make sure vpshere shuts down VM

* Wait for 60 seconds for VM to shutdown
* Send power-off command if it still up

Signed-off-by: Maria Shaldibina <mariash@pivotallabs.com>
Set ntp server in vsphere manifest properties section

Director config file is using ntp server configuration from
manifest properties section.

Signed-off-by: Maria Shaldibina <mariash@pivotallabs.com>
Decrease the number of parallel tests on traivs to 4

This is to prevent Travis from killing integration tests

Signed-off-by: Maria Shaldibina <mariash@pivotallabs.com>