Remove LDAP ping test

ICMP ping doesn't work in all networks and can give misleading results.
ping can also take about 30 seconds to return in case of error.
Therefore, use a timeout mechanism to prevent hanging for too long in
case an LDAP server is not responding.
Add sb2install: dependancy handling

Signed-off-by: Carsten Munk <carsten.munk@gmail.com>