different distributions have different names

on my Gentoo box the script is called /usr/bin/VBoxManage, on my arch
box it is called /usr/bin/vboxmanage; maybe we need a more generic
approach for this
wrote some functions for easier SSH cmd execution
now ensuring that VMs are started in run_tests.sh, too
small bugfix

return command does not return the exit code of the command; instead one
has to use $?
bugfix: when $content is empty this fails
added ssh_exec_ip() and now using ssh_exec in tests
now using ssh_exec in lib
now using 'function test_' as regexp for tests

The more generic regexp ('test_') also matched on each test line
containing 'test_', e.g. 'test_db'
added a status message for setting up postgresql
fix: ensure that pg_versions is defined before we use it
fix: typo, ssh_cmd_ip accepts the IP, a vm name isn't even defined
more robustness and more logging
revamped pg_config_<node> support

Now we support absolute file pathes for pg_config_<node> and we no
longer enforce placement in data/
added some logging for starting/stopping postgres versions
began testing of standby register
fix: we now are able to use a different data directory