Update install-crowbar-native.sh to reflect the evolution of the admin node.
Try up to 3 times to converge the admin node.

Use the shiny new crowbar converge command to do it.
Script the creation of an admin network.
Initialize the default timezone from the timezone set on the admin node

This is less confusing for users.
Merge pull request #1901 from dirkmueller/set_default_timezone

Initialize the default timezone from the timezone set on the admin node