Fixes # 2172
Merge pull request #2223 from czpython/fixes-2172

Fixes # 2172
Added missing django.db.models import to docs
Merge pull request #2230 from dbrgn/docs_import_fix

Added missing django.db.models import to docs
Unicode fix to make Sphinx 1.2b2 happy
Merge pull request #2233 from yakky/feature/unicode_fix_docs_test

Unicode fix to make Sphinx 1.2b2 happy
Fix placeholder documentation
Fix another paragraph
Documentation revision. Thanks @mkoistinen
Merge pull request #2249 from yakky/feature/ph_docs

Fix PlaceholderField documentation
Add more thorough check to language configuration in 'check' command
Add warning about using the correct language codes
fixing punctuation in the README's intro
Merge pull request #2269 from mikedory/develop

fixing punctuation in the README's intro
Add language code example to check function to clarify possible language/locale confusion
Fix whitespace issue
Merge pull request #2263 from yakky/feature/docs_langs

Checks against common error in language settings
Update setup.py to require django-mptt==0.6 for python 3 support
Relax django-mptt specs to allow django-mptt==0.5.2
seems to me like database setup has nothing to do with templates, probably an error in the hierarchical levvel setting - fixing this by setting some of the parts one level up