(QENG-967) Disable iptables on el hosts bringup.

Also fixes bug in `disable_iptables` where per-array-element was invoking wrong
method. Looks like `disable_iptables` was originally copied from
`copy_ssh_to_root`

Also adds rspec for Beaker::Hypervisor.configure

Signed-off-by: Wayne <wayne@puppetlabs.com>
(QENG-1231) add onpass option to --preserve-hosts
* add spec tests similar to onfail spec tests
* add cleanup to rescue when --preserve-hosts onpass
* add help statement for onpass
remove non-capture from regex groups
Merge pull request #377 from waynr/feature/qeng-967-disable-iptables-on-el-hosts

(QENG-967) Disable iptables on el hosts bringup.
(QENG-270) Added ntp_server as an option for host config

Before this, you couldn't specify an ntp server, so if you used the timesync option, it would only use the hard-coded value 'pool.ntp.org'.
This was a problem because occasionally that service couldn't be reached.  In order to fix this, we've allowed people to specify a server, so that they can get more reliable ntp services, and not see failures based on being able to reach one.
(QENG-1205) EC2 zombie killer can fail when instance not found

- better error handling around zombie killing
Merge pull request #490 from anodelman/ec2

(QENG-1205) EC2 zombie killer can fail when instance not found
Merge pull request #486 from kevpl/qeng270_ntp_addoption

(QENG-270) Added ntp_server as an option for host config
Merge pull request #475 from er0ck/feature/master/QENG-1231-preserve_hosts_onpass

(QENG-1231) add onpass option to --preserve-hosts