Adjust form label size

The sheet admin/css/forms.css makes labels too small
so we replace the original bootstrap size.
Merge pull request #147 from interlegis/master

Adjust form label size
Empty AdminModels as StackedInlines causing crashes

Example:

models.py:

class Profile(models.Model):
    user = models.OneToOneField(User)

admin.py:

from django.contrib.auth.admin import UserAdmin
from models import Profile

class ProfileInline(admin.StackedInline):
    model = Profile

class CustomUserAdmin(UserAdmin):
    inlines = (ProfileInline, )

admin.site.unregister(User)
admin.site.register(User, CustomUserAdmin)

---------------------

Clicking on the "User" object in the admin under native django admin you will
see a line with the Profile object and its id.  Under
django-admin-bootstrapped you get an exception:

ValueError: max() arg is an empty sequence

inside of the bootstrapped_goodies_tags.py file.

Upon further inspection it looks like fieldset_column_width() and
form_fieldset_column_width() both assume there are fields in the fieldset.
The column_width() method makes a similar assumption which could cause a
divide by zero problem.

Wrapped max() and division calls to stop these problems.
Merge pull request #148 from cltrudeau/master

Don't raise exceptions with empty objects
Cleanup application related fields retrieval

Introducing new tags:
- render_app_name
- render_app_label
- render_app_description

This should replace the entries like:

{% render_with_template_if_exist app.name|lower|add:"/admin_app_name.html" app.name %}
by
{% render_name app%}

While at it use the fix improper use of app.name with template paths. The template
path should not be built using app.name as it is the verbose name that is pushed to
the template system. From https://github.com/django/django/blob/master/django/contrib/admin/sites.py:

app_dict[app_label] = {
    'name': apps.get_app_config(app_label).verbose_name,
    'app_label': app_label,
    'app_url': reverse(
        'admin:app_list',
        kwargs={'app_label': app_label},
        current_app=self.name,
    ),
    'has_module_perms': has_module_perms,
    'models': [model_dict],
}
Update CHANGELOG
Update README regarding changing application name

Deprecate the template solution in favour of the upstream one.