Add onclick handler to 'Post...' button

- handler is simple function that just returns the pseudonym,
  which is then consumed by the Facebook post action
- simple Jasmine test to verify that the function's returning
  the correct value
Remove link to mystery JS

Commented out, so why keep it?
Remove commented-out block

These were useful tests when starting, less worthwhile now.
Add templates for long JS strings

So far, there's only one custom message (post to Facebook), but could
have more in the inventory: errors and so on.