[meta] Examples projects without tests

Taking an accounting of the state of testing in Examples for Developers.

These either don't have tests, or have tests that don't show up under Examples on the testing page:

Need tests:

• js_example
• tabledrag_example
• vertical_tabs_example

Have tests that aren't run:

• field_permission_example (has test)
• token_example #2017223: token_example's tests = can of worms.

Ideally they'd all have tests, if only to make sure they install properly.

The ones which are skipped are somewhat puzzling. I wrote the field_permission_example one, and it ran through a local Drupal installation, so something has changed since then.

Also theming_example test fails under PHP 5.4.4 but is happy under 5.2.17.

...And some D7 testing-related issues:
#1249022: Add tests for AjAX Example
#1100190: Improve doxygen formatting of .test files
#786156: Update the SimpleTest tutorial to reflect the 'mock module' pattern.
#1630762: Configuration example for D7, so that the upgrade path to D8 may be demonstrated.
#1862458: Cron_example fails testbot