#10 Updating lib/util.php

Function common_ensure_session had unnecessary code and error suppression, it is now updated. Also ran php-cs-fixer in the file.

I guess you can squash 477eec7ba7 and 76f3dda327 . The commit message can be something like

Cleanup and documentation of common_ensure_session
- Remove redundant branch
- Remove error suppression of session_start()

@diogo done :)