Change default framework view (issue #17)

This version introduces multiple enhancements:

modified view of 404 page

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

Modified:   /BLUE_FRAMEWORK/cfg/tree.xml
            -- Added --
                styles and modules
            -- Updated --
                changed 404 page title to language code
            -- Removed --
                unused styles and scripts
Modified:   /BLUE_FRAMEWORK/cfg/lang/core_en-GB.php
            -- Updated --
                changed 404 page title

Modified:   /BLUE_FRAMEWORK/cfg/lang/core_pl-PL.php
            -- Updated --
                changed 404 page title

Modified:   /BLUE_FRAMEWORK/elements/layouts/404.html
            -- Updated --
                changed whole page structure

Modified:   /BLUE_FRAMEWORK/elements/css/styles.css
            -- Added --
                added some styles for 404 page view