Enabled ASCIIFolding in Elasticsearch backend
Fixed unicode encoding issues on Python 2
Implement `Page.parent_page_types`

Similar to `Page.subpage_types`, but restricts which pages can have a
specific page type as a child.

Useful for Blog posts being restricted to Blog list pages, or similar
things.
Add tests for new `Page.parent_page_types` setting
Restrict child page types when creating them

The list of allowed child page types was restricted, but if you could
guess the URL to create a disallowed page type, nothing would stop you
creating it. Fixes a failing test case.
Force `Page._clean_sub/parent_page_types` to be a list
Add `Page.parent_page_types` to the docs
Replace all calls to clean_subpage_types with allowed_subpage_types

`clean_subpage_types` should not be part of the public API any more, and
`allowed_subpage_types` should replace it in all instances.
Fix indentation of docstings
Fix errors raised with `resolve_model_string`

It now raises `ValueError` for a badly formatted string, and `NameError`
if it can not find the model. Error messages are not translated. Edit
handlers now use the function.
`resolve_model_string` now raises `LookupError`

Django 1.7 raises a `LookupError` when looking for a model that does not
exist. This brings the code in to line with Django. The `LookupError`
from Django is allowed to propagate in 1.7, and a `LookupError` is now
raised instead of a `NameError` in 1.6.

All code using `resolve_model_string` has been changed to catch the new
errors.
Additions to the 'getting started' documentation so that we're not under-selling the demo site as a way to get started
Merge branch 'stable/0.6.x'
Remove content_type template filter from the project template - fixes #626
Make Page.copy also copy revisions
Clear submitted_for_moderation and approved_go_live_at of copied revisions
Merge pull request #568 from kaedroho/page-copy-revisions

Make Page.copy also copy revisions
release note for #568
Merge branch 'feature/parent_page_types' of https://github.com/takeflight/wagtail into takeflight-feature/parent_page_types
copyediting on parent_page_types documentation