WMCO does not wait for instance to reboot properly

WMCO does not properly deduce when a reboot is complete. Currently, it tries to initialize an SSH connection directly after issuing the reboot request -- this can lead to timing issues where the reboot hasn't occurred yet and the initial SSH connection is still active, so WMCO thinks the reboot is done and proceeds with node configuration. Then, a bit later, the reboot actually is underway and WMCO errors out and has to re-init SSH and restart configuration.

4.14 (and below through 4.10)

Always

1. Use a Windows image that does not have the Containers feature enabled already 
2. Have WMCO try to configure the instance as a node
3. Timing error will show when restarting instance after turning on containers feature

WMCO's check if the instance is reachable via SSH is too quick and incorrectly assumes the reboot has been completed right away, which leads to configuration failure later as it can not run powershell commands over SSH when reboot is underway.

WMCO should wait/check for reboot in a more complete manner to avoid false positives. 

Perhaps waiting for the node to be unreachable first, and then waiting for it to be reachable again could solve this?