Description of problem:
dnf group install crashes when used to install group which name was translated and non-ascii characters were used.
For example installing "Pracovní plochy KDE Plasma" (czech translation for KDE group).

Version-Release number of selected component:
dnf-0.3.10-2.giteb9dddb.fc20

Additional info:
reporter:       libreport-2.1.6
cmdline:        /usr/bin/python /bin/dnf group install 'Pracovn\xc3\xad' plochy KDE Plasma
executable:     /bin/dnf
kernel:         3.11.0-0.rc4.git0.2.fc20.x86_64
runlevel:       unknown
type:           Python
uid:            0

Truncated backtrace:
cli.py:894:install_grouplist:UnicodeDecodeError: 'ascii' codec can't decode byte 0xc3 in position 7: ordinal not in range(128)

Traceback (most recent call last):
  File "/bin/dnf", line 35, in <module>
    main.user_main(sys.argv[1:], exit_code=True)
  File "/usr/lib/python2.7/site-packages/dnf/cli/main.py", line 292, in user_main
    errcode = main(args)
  File "/usr/lib/python2.7/site-packages/dnf/cli/main.py", line 64, in main
    return _main(base, args)
  File "/usr/lib/python2.7/site-packages/dnf/cli/main.py", line 133, in _main
    result, resultmsgs = cli.run()
  File "/usr/lib/python2.7/site-packages/dnf/cli/cli.py", line 1293, in run
    return self.command.doCommand(self.base.basecmd, self.base.extcmds)
  File "/usr/lib/python2.7/site-packages/dnf/cli/commands.py", line 883, in doCommand
    return self.base.install_grouplist(extcmds)
  File "/usr/lib/python2.7/site-packages/dnf/cli/cli.py", line 894, in install_grouplist
    msg = _('Warning: Group %s does not exist.') % group_string
UnicodeDecodeError: 'ascii' codec can't decode byte 0xc3 in position 7: ordinal not in range(128)

Local variables in innermost frame:
grouplist: ['Pracovn\xc3\xad', 'plochy', 'KDE', 'Plasma']
pkgs_used: []
self: <dnf.cli.cli.YumBaseCli object at 0xf0cd10>
group_string: 'Pracovn\xc3\xad'
groups: []
matched: []