Catch 'jav\tascript:alert("XSS")' as a bad URL

The URL checker from html5lib was used as inspiration. As html5lib is
based on the same ideas that browsers (should) use for parsing and
checking, this solution should be much more robust.
Tabbing from password field goes to Submit
Use latest_revision_created_at in sitemap gen

Much faster than looking it up manually for every page in the site
Added failing test
created_at of PageRevisions is now copied on page copy
Added Django 1.7 migration
`unicode()` doesn't exist in PY3, changed to `str()`
Switched usage of `str()` to `six.text_type()`

Removed unused import
Merge pull request #736 from jsma/py3-fix

`unicode()` doesn't exist in PY3, changed to `str()`
Merge branch 'bug/url-check' of https://github.com/takeflight/wagtail into takeflight-bug/url-check
Merge branch 'takeflight-bug/url-check'
release note for #463
Added logging for most page operations
Log page deletions
Added logging for moderation approval/rejection
Merge branch 'logging' of https://github.com/kaedroho/wagtail into kaedroho-logging
Use new_url_path in page move log
Merge branch 'login_page_tabindex' of https://github.com/nimasmi/wagtail into nimasmi-login_page_tabindex
Merge branch 'nimasmi-login_page_tabindex'
Merge branch 'logging' of https://github.com/kaedroho/wagtail into kaedroho-logging