Use PSR-0 autoloader also on index_dev.php controller. Refs #2293
Export PTRACK_SOCKETPATH environment variable. Refs #2029

The ptrack wrapper opens a listening socket on the given path. To run
ptrack unprivileged, this variable must be passed to child processes
by sudo command.
Suppressed display_errors.

Error messages are directed to syslog. You can still use index_dev.php
controller to see PHP errors in server response.
Fixed CSS ButtonList class margin. Refs #2029