fatal kwarg on option does not allow --help on cli for non existing config files

[s0undt3ch]

When an option in a schema has the fatal kwarg set to True, we cannot issue a `--help` on the console, raises ConfigParser.NoOptionError.
This happens while there's no config file yet.

This should only happen if not passing `--help` and should be raised in a cleaner way, not something like:
Traceback (most recent call last):
  File "tests/cfglue_test.py", line 65, in <module>
    op, opts, args = schemaconfigglue(scp)
  File "/home/vampas/projects/.virtual_python/lib/python2.6/site-packages/configglue/pyschema/glue.py", line 62, in schemaconfigglue
    kwargs['default'] = parser.get(section.name, option.name)
  File "/home/vampas/projects/.virtual_python/lib/python2.6/site-packages/configglue/pyschema/parser.py", line 457, in get
    raw, vars)
  File "/usr/lib/python2.6/ConfigParser.py", line 541, in get
    raise NoOptionError(option, section)
ConfigParser.NoOptionError: No option 'network' in section: '__main__

[s0undt3ch (ufs)]

Seems that like this we can't event write a default config file with the basic schema defaults.