Make full example modules (issue #20)

This version introduces multiple enhancements:

added module with core template example
also added correct page in tree structure

Details of additions/deletions below:
--------------------------------------------------------------

Added:      /BLUE_FRAMEWORK/modules/example_core_templates/example_core_templates.php
            -- Added --
                example module class

Added:      /BLUE_FRAMEWORK/modules/example_core_templates/lang/example_core_templates_en-GB.php
            -- Added --
                english translations

Added:      /BLUE_FRAMEWORK/modules/example_core_templates/lang/example_core_templates_pl-PL.php
            -- Added --
                polish translations

Added:      /BLUE_FRAMEWORK/modules/example_core_templates/layouts/index.html
            -- Added --
                example tamplate

Modified:   /BLUE_FRAMEWORK/cfg/tree.xml
            -- Added --
                example_core_templates to example structure