Remove values without a name attribute (fixes: #5).

I took a quick look at it and it seems that the bug_status list of dicts has an additional item, that features no name key. See the pretty-print below:
```
$ pp values (bzlib/bugzilla.py:167)
[{'can_change_to': [{'comment_required': False, 'name': 'UNCONFIRMED'},
                    {'comment_required': False, 'name': 'CONFIRMED'},
                    {'comment_required': False, 'name': 'IN_PROGRESS'}],
  'is_open': True,
  'sort_key': 0,
  'sortkey': 0,
  'visibility_values': []},
 {'can_change_to': [{'comment_required': False, 'name': 'CONFIRMED'},
                    {'comment_required': False, 'name': 'IN_PROGRESS'},
                    {'comment_required': False, 'name': 'RESOLVED'}],
  'is_open': True,
  'name': 'UNCONFIRMED',
  'sort_key': 100,
  'sortkey': 100,
  'visibility_values': []},
 {'can_change_to': [{'comment_required': False, 'name': 'IN_PROGRESS'},
                    {'comment_required': False, 'name': 'RESOLVED'}],
  'is_open': True,
  'name': 'CONFIRMED',
  'sort_key': 200,
  'sortkey': 200,
  'visibility_values': []},
 {'can_change_to': [{'comment_required': False, 'name': 'CONFIRMED'},
                    {'comment_required': False, 'name': 'RESOLVED'}],
  'is_open': True,
  'name': 'IN_PROGRESS',
  'sort_key': 300,
  'sortkey': 300,
  'visibility_values': []},
 {'can_change_to': [{'comment_required': False, 'name': 'UNCONFIRMED'},
                    {'comment_required': False, 'name': 'CONFIRMED'},
                    {'comment_required': False, 'name': 'VERIFIED'}],
  'is_open': False,
  'name': 'RESOLVED',
  'sort_key': 400,
  'sortkey': 400,
  'visibility_values': []},
 {'can_change_to': [{'comment_required': False, 'name': 'UNCONFIRMED'},
                    {'comment_required': False, 'name': 'CONFIRMED'}],
  'is_open': False,
  'name': 'VERIFIED',
  'sort_key': 500,
  'sortkey': 500,
  'visibility_values': []}]
```
An easy fix for this is to filter out any item without a name attribute. With this change applied, updating a bug does work again. I also checked the subcommands 'new' and 'fields' and they seem to work as expected. Please review the change and provide feedback.