Description of problem:
If user specify command like

ipa-server-install --setup-dns --forwarder=102.102.160.2  -r TESTRELM.TEST -p
password -a password --zonemgr=T??ko@redhat.com -U

installation goes on and while installation steps of DNS, it fails with error
like following

<snip>

Configuring DNS (named)
  [1/12]: generating rndc key file
  [2/12]: adding DNS container
  [3/12]: setting up our zone
  [error] ConversionError: invalid 'admin_email': domain name
'T??ko.redhat.com' should be normalized to: t?ako.redhat.com
ipa.ipapython.install.cli.install_tool(Server): ERROR    invalid 'admin_email':
domain name 'T??ko.redhat.com' should be normalized to: t?ako.redhat.com

</snip>

Version-Release number of selected component (if applicable):
ipa-server-4.2.0-15.el7.x86_64

How reproducible:
100%

Steps to Reproduce:
1. Start fresh installation of IPA server with zonemgr option and unicode
string as argument.

Actual results:
Installation fails at DNS configuration phase with
ERROR    invalid 'admin_email': domain name 'T??ko.redhat.com' should be
normalized to: t?ako.redhat.com

Expected results:
Installation should check before start and warn user beforehand.

Additional info:
Related to
1. https://fedorahosted.org/freeipa/ticket/4771
2. https://bugzilla.redhat.com/show_bug.cgi?id=1163849