Description of problem:
Run 'atomic-openshift-installer install' in unattended way, once no "connect_to", "master" or "node" facts defined in the installer config yaml file, the installer would throw an exception, which is unfriendly. 

Version-Release number of selected component (if applicable):
atomic-openshift-utils-3.0.12-1.git.0.4c09c5b.el7aos.noarch

How reproducible:
Always

Steps to Reproduce:
1.Prepare an installer config yaml file which not contains "connect_to" facts
2.[root@openshift-v3 ~]# atomic-openshift-installer -u -c installer.cfg.yml install
Traceback (most recent call last):
  File "/usr/bin/atomic-openshift-installer", line 9, in <module>
    load_entry_point('ooinstall==3.0.0', 'console_scripts', 'oo-install')()
  File "/usr/lib/python2.7/site-packages/click/core.py", line 664, in __call__
    return self.main(*args, **kwargs)
  File "/usr/lib/python2.7/site-packages/click/core.py", line 644, in main
    rv = self.invoke(ctx)
  File "/usr/lib/python2.7/site-packages/click/core.py", line 988, in invoke
    Command.invoke(self, ctx)
  File "/usr/lib/python2.7/site-packages/click/core.py", line 837, in invoke
    return ctx.invoke(self.callback, **ctx.params)
  File "/usr/lib/python2.7/site-packages/click/core.py", line 464, in invoke
    return callback(*args, **kwargs)
  File "/usr/lib/python2.7/site-packages/ooinstall/cli_installer.py", line 442, in cli
    oo_cfg = OOConfig(ctx.obj['configuration'])
  File "/usr/lib/python2.7/site-packages/ooinstall/oo_config.py", line 85, in __init__
    self._read_config()
  File "/usr/lib/python2.7/site-packages/ooinstall/oo_config.py", line 104, in _read_config
    self.hosts.append(Host(**host))
  File "/usr/lib/python2.7/site-packages/ooinstall/oo_config.py", line 48, in __init__
    raise OOConfigInvalidHostError("You must specify either and 'ip' " \
ooinstall.oo_config.OOConfigInvalidHostError: You must specify either and 'ip' or 'hostname' to connect to.

3. Prepare an installer config yaml file which not contains "master" or "node" facts
4. [root@openshift-v3 ~]# atomic-openshift-installer -u -c installer.cfg.yml install
Traceback (most recent call last):
  File "/usr/bin/atomic-openshift-installer", line 9, in <module>
    load_entry_point('ooinstall==3.0.0', 'console_scripts', 'oo-install')()
  File "/usr/lib/python2.7/site-packages/click/core.py", line 664, in __call__
    return self.main(*args, **kwargs)
  File "/usr/lib/python2.7/site-packages/click/core.py", line 644, in main
    rv = self.invoke(ctx)
  File "/usr/lib/python2.7/site-packages/click/core.py", line 988, in invoke
    Command.invoke(self, ctx)
  File "/usr/lib/python2.7/site-packages/click/core.py", line 837, in invoke
    return ctx.invoke(self.callback, **ctx.params)
  File "/usr/lib/python2.7/site-packages/click/core.py", line 464, in invoke
    return callback(*args, **kwargs)
  File "/usr/lib/python2.7/site-packages/ooinstall/cli_installer.py", line 442, in cli
    oo_cfg = OOConfig(ctx.obj['configuration'])
  File "/usr/lib/python2.7/site-packages/ooinstall/oo_config.py", line 85, in __init__
    self._read_config()
  File "/usr/lib/python2.7/site-packages/ooinstall/oo_config.py", line 104, in _read_config
    self.hosts.append(Host(**host))
  File "/usr/lib/python2.7/site-packages/ooinstall/oo_config.py", line 53, in __init__
    "You must specify each host as either a master or a node.")
ooinstall.oo_config.OOConfigInvalidHostError: You must specify each host as either a master or a node.


Actual results:


Expected results:
Should give friendly prompt just as when missing "ip, hostname..."
[root@openshift-v3 ~]# atomic-openshift-installer -u -c installer.cfg.yml install
For unattended installs, facts must be provided for all masters/nodes:
Host "xxx" missing facts: ip, hostname


Additional info: