Description of problem:

Traceback when selecting "Proceed with the values shown" in fusor-installer, if some of the network fields are blank or have bad values (e.g., 192.168.0.256 for an IP address):

****
# fusor-installer 

Select which NIC to use for provisioning:
1. eth0
2. eth1
?  2

The installer can configure the networking and firewall rules on this machine with the configuration shown below. Default values are populated from this machine's existing networking configuration.

If you DO NOT want to configure networking, select the option 'Do not configure networking' from the list below.

Modify settings as needed, and then proceed with the installation:
1.      Proceed with the values shown
2.           Network interface | eth1
3.                    Hostname | dhcp-8-59-158.cfme.lab.eng.rdu2.redhat.com
4.                  IP address | 
5.                Network mask | 
6.                Host gateway | 10.8.59.254
7.        DHCP Network address | 
8.            DHCP range start | 
9.              DHCP range end | 
10.               DHCP gateway | 10.8.59.254
11.              DNS forwarder | 10.11.5.19
12.                     Domain | cfme.lab.eng.rdu2.redhat.com
13.                Foreman URL | https://dhcp-8-59-158.cfme.lab.eng.rdu2.redhat.com
14.              NTP sync host | 0.rhel.pool.ntp.org
15.                  Time zone | America/New_York
16.        BMC feature enabled | false
17.       BMC default provider | ipmitool
18. Do not configure networking
19. Do not configure firewall
20. Cancel installation
1
/usr/share/ruby/ipaddr.rb:475:in `initialize': address family must be specified (IPAddr::AddressFamilyError)
	from /usr/share/katello-installer/hooks/lib/provisioning_wizard.rb:285:in `new'
	from /usr/share/katello-installer/hooks/lib/provisioning_wizard.rb:285:in `validate_own_gateway'
	from /usr/share/katello-installer/hooks/lib/base_wizard.rb:63:in `block in validate'
	from /usr/share/katello-installer/hooks/lib/base_wizard.rb:61:in `map'
	from /usr/share/katello-installer/hooks/lib/base_wizard.rb:61:in `validate'
	from /usr/share/katello-installer/hooks/lib/base_wizard.rb:38:in `start'
	from /usr/share/katello-installer/hooks/lib/provisioning_wizard.rb:53:in `start'
	from /usr/share/katello-installer/hooks/pre_validations/10-gather_and_set_fusor_values.rb:5:in `block (4 levels) in load'
	from /usr/share/gems/gems/kafo-0.6.5.9/lib/kafo/hooking.rb:32:in `instance_eval'
	from /usr/share/gems/gems/kafo-0.6.5.9/lib/kafo/hooking.rb:32:in `block (4 levels) in load'
	from /usr/share/gems/gems/kafo-0.6.5.9/lib/kafo/hook_context.rb:13:in `instance_exec'
	from /usr/share/gems/gems/kafo-0.6.5.9/lib/kafo/hook_context.rb:13:in `execute'
	from /usr/share/gems/gems/kafo-0.6.5.9/lib/kafo/hooking.rb:49:in `block in execute'
	from /usr/share/gems/gems/kafo-0.6.5.9/lib/kafo/hooking.rb:47:in `each'
	from /usr/share/gems/gems/kafo-0.6.5.9/lib/kafo/hooking.rb:47:in `execute'
	from /usr/share/gems/gems/kafo-0.6.5.9/lib/kafo/kafo_configure.rb:92:in `execute'
	from /usr/share/gems/gems/clamp-0.6.2/lib/clamp/command.rb:67:in `run'
	from /usr/share/gems/gems/clamp-0.6.2/lib/clamp/command.rb:125:in `run'
	from /usr/share/gems/gems/kafo-0.6.5.9/lib/kafo/kafo_configure.rb:116:in `run'
	from /usr/sbin/fusor-installer:63:in `<main>'
****

Version-Release number of selected component (if applicable):

QCI-1.0-RHEL-7-20160307.t.0

How reproducible:

100%

Steps to Reproduce:
1.) Run fusor-installer
2.) Select option #1 without filling out all fields.
3.) See traceback.

Actual results:

Traceback.

Expected results:

No traceback, prompt the user to fix missing/invalid fields.

Additional info: