updated test case for page attribute template tag.
Add link target support

Possible targets:
same window (<<empty>>)
new window (_blank)
parent window (_parent)
topmost frame (_top)

Credit to bendavis78 for implementation, this commit just generalizes.
Add tests for LinkPlugin
Translate the copied language plugin also. This is needed since the string cannot be translated (ugettext_lazy) in the settings.py file.
tweak the clean_overwrite_url method to check that page.pk is not the page.publisher_public_id
Adding pop-up blocker warning

Signed-off-by: F. Gabriel Gosselin <gabriel@evidens.ca>
fixed toolbar to only display items for which the user has permissions to
simplified the toolbar permissions
Requirements.txt files for testing.
A test for issue #1211 and pull request #1255
Making cms/models more pep8 compliant

Fixing specially:
		* Trailing whitespaces
		* Number of empty lines between classes/methods
		* Comments
`copy_plugins_to` should return copied plugins for additional
post-processing to be possible.
This would fix the django-cms issue #1304 (https://github.com/divio/django-cms/issues/1304) that I raised today.

Background: when CMS is configured not to be at root level but at a sub site .. e.g. /content, then the multilingual url prefixes are generated correctly for HREFs, resulting in /en/content/otherpath

BUT all FORM urls end up /content/en/otherpath , and the same applies to the preview URLs in the admin….

This change fixes that, making sure all urls end up constantly as /en/content/otherpath...
removed handling of iterables in plugin_pool.register_plugin and plugin_pool.unregister_plugin
Merge branch 'release/2.3rc2'
Fixed a logic error inlazy menu queryset checks and minor optimizations (thanks to @piquadrat for pointing this out)
Use {% with %} as a further optimization
Fixed stupid typo
cache the result of the global page permission query on the request object

this saves a lot of duplicate queries (1 per page in the tree if my calculations are correct)
Fixed incorrect fuzzy translations