Fix warning in tree.php on empty library folder

Fix warning of undefined variable
Merge pull request #6 from gorekee/patch-1

Fix warning in tree.php on empty library folder
Merge pull request #7 from filp/master

Use correct HTML5 charset tag
Add ability to move config to config.php file
Document config changes in bundled index.md
Merge pull request #8 from filp/feature/split-config

(optionally) define configuration in config.php file (outside VCS)
fix illegal offset type in tree module
Fix router logic to handle undefined actions