* Add tests to check the DoS prevention code.

* Add `._pasteObjects()` to be able to paste objects without limits.

Fixes #217.

Test that `str.format` checks security for accessed keys and items.

The PR was merged, but we still need a checkout at this moment.

The real fix is in the AccessControl package, which we checkout on a specific branch here.
Part of PloneHotfix20171128.

Make Redirect unavailable as url [2.13]

Skip IPv6 tests on Travis, as it is not supported.

Using the previously described variant using the index led to a broken installation because `pip` installs `Products.ZCatalog` 4.x. It expects to find `products.zcatalog` in the index. (Even downgrading to pip 1.5 does not help.)

This closes #194.

Explicitly require Manager role for `AltDatabaseManager`.

'bin/buildout -n' did not help.

That fixed the build for me locally.
Error on Travis:

$ bin/buildout
Getting distribution for 'zc.buildout<2.4.dev'.
While:
  Installing.
  Loading extensions.
  Getting distribution for 'zc.buildout<2.4.dev'.
An internal error occurred due to a bug in either zc.buildout or in a
recipe being used:
Traceback (most recent call last):
  File "/home/travis/build/zopefoundation/Zope/eggs/zc.buildout-2.9.3-py2.7.egg/zc/buildout/buildout.py", line 2123, in main
    getattr(buildout, command)(args)
  File "/home/travis/build/zopefoundation/Zope/eggs/zc.buildout-2.9.3-py2.7.egg/zc/buildout/buildout.py", line 637, in install
    self._load_extensions()
  File "/home/travis/build/zopefoundation/Zope/eggs/zc.buildout-2.9.3-py2.7.egg/zc/buildout/buildout.py", line 1163, in _load_extensions
    newest=self.newest, allow_hosts=self._allow_hosts)
  File "/home/travis/build/zopefoundation/Zope/eggs/zc.buildout-2.9.3-py2.7.egg/zc/buildout/easy_install.py", line 913, in install
    return installer.install(specs, working_set)
  File "/home/travis/build/zopefoundation/Zope/eggs/zc.buildout-2.9.3-py2.7.egg/zc/buildout/easy_install.py", line 714, in install
    for dist in self._get_dist(req, ws):
  File "/home/travis/build/zopefoundation/Zope/eggs/zc.buildout-2.9.3-py2.7.egg/zc/buildout/easy_install.py", line 570, in _get_dist
    dist = self._env.best_match(requirement, ws)
  File "/home/travis/virtualenv/python2.7.9/lib/python2.7/site-packages/pkg_resources/__init__.py", line 1040, in best_match
    dist = working_set.find(req)
  File "/home/travis/virtualenv/python2.7.9/lib/python2.7/site-packages/pkg_resources/__init__.py", line 672, in find
    raise VersionConflict(dist, req)
VersionConflict: (zc.buildout 2.9.3 (/home/travis/build/zopefoundation/Zope/eggs/zc.buildout-2.9.3-py2.7.egg), Requirement.parse('zc.buildout<2.4.dev'))

If you use experimental.publishtraverse and try to call manage_pack,
it warns that the object (the manage_pack function) has no roles.
In strict mode it will fail.
This is an indication that the function *might* be available for anonymous users.
That is not the case here, but being strict seems good.

* Test that `str.format` checks the security for attributes that are accessed.

Part of PloneHotfix20170117.

This needs https://github.com/zopefoundation/AccessControl/pull/23
This was merged, but not released yet, so we add AccessControl to auto-checkout for now.

* AccessControl has a release, no need for auto-checkout anymore.