Action menu items were misaligned because of change from smallicon to icon.

- Properly validate the displayer API response before sending the
verification email.
- Properly validate the displayer API response before creating the
saved connection.

Lang string fix.

The section highlighting code was re-written in parallel to font-awesome - so we need
to apply the same font-awesome tweaks here now.

Don't call the deprecated lang string.

In this commit I removed redirects that potentially could break the Web
Services layer.
Instead doing redirect inside APIs I return a special flag that is
properly checked.

Small refactor to avoid duplication in the Web Service

This is a big refactor to avoid code duplication in the new WS.
Basically I’ve moved code from the page and renderer to the lesson
class.
New code is into methods, there are no code functionality changes (just
minor fixes in comments).

Some code that will be used by Web Services was moved, we created new
methods to avoid code duplication:
- To generate the lesson messages on page view
- To check the time restrictions in a current attempt