Update Travis build versions
Update tags
Update unit test files
Add a multisite PHPUnit config file for easier multisite testing
More comprehensive tests for admins
Tests for all default roles
Increase the specificity of the `switch_to_old_user` and `switch_off` nonces by including the corresponding user ID in each.
Some more query args to remove when redirecting
Tests for switching off
Separate the Super Admin tests
Tests for users with no role