Show inactive parameter implemeted as an operator

As described in this core developer thread:
http://plone.293351.n2.nabble.com/plone-app-collection-displaying-inactive-objects-for-anonymous-users-td7570118.html

This pull requests does the following:
1. Adds an showInactive operator which checks for a value from the Roles vocabulary.
2. Adds a roles vocabularies since plone.app.vocabularies roles does not contain the Anonymous role.
3. Passes show_inactive: true or false to the catalog query depending on the role selection.

This is useful for situations where you want for a particular collection to show inactive objects for a number of roles, including Anonymous without globally affecting the "Access inactive portal content" permission.

I expect for the registered vocabulary to be overkill but I am looking forward to suggestions that would simplify this action.

If this pull request would be accepted I will need to add an upgrade step to plone.app.upgrade since we have new entries within registry.xml