Prepared rewrite of framework bootstrap:

Prepared rewrite of framework bootstrap:
- added initial class 'BootstrapFramework' which doesn't need to be
  instanciated as only static methods will come
- $cfg in inc/config.php is now being unset, it is not good coding practice
  to then use it outside the scope of the included file
- you then need to get $cfg again from
  FrameworkConfiguration::getSelfInstance() to be able to set/get configuration
  entries.
- added note how to deal with inc/config/config-local.php-dist which is an
  example how to use it in your own applications.
- minor improvements (comments)

Signed-off-by: Roland Häder <roland@mxchange.org>