Fixed some code
- "Silex.php": coding style
- "bootstrap.php": start session
- "config.example.json": small comment addition
- "Database.php": added getAdapter() method and fixed PHPDocs description
Fixed Version utility class
- optimized code
- changed return to:
  - version1 < version2 -> -1
  - version1 = version2 ->  0
  - version1 > version2 ->  1
- added missing operators
- added rc release state