Improving BasePageProvider to make inheritance simpler

Two methods have been added to class aria.pageEngine.pageProviders.BasePageProvider:
processSiteConfiguration and processPageDefinition. They are called, respectively, before sending the site configuration and page definitions back to the page engine.

This makes it possible to extend the BasePageProvider class by only implementing those two methods.
Page engine - document title is set also in hash-based navigation

When "navigation" is set to "hash" in the site configuration, the title of the page (specified in the page definition) is used to change the title of the document.
This was previously done only in history-based navigation
Improvement of page engine tests

Tests for the PageEngine class are no longer template tests.