changed init scripts to log the stdout and stderr of vishnu services in /var/log/vishnu/<service_name>.log
fixed tickets #444 and 445: related to the missing of vishnulib.jar in binary packages
removed unecessary file
restore accidentally deleted contents
avoid creating direcory in init scripts
fixed ticket #435: improving error message on empty session id
bugfix: prevent vishnu sessions pid files corruption

add a file lock to disable concurrent accesses to ~/.vishun/sessions/<pid> file
fixes #135
bugfix: add exception handling code to vishnu session pid files save

Cf. previous commit, in some cases (rare ?), file locking code throws an exception.