Added options to configure processname for logging. Usefull when having multiple installations on the same machine.

Processname in the log is determined by the 'logging.processname' configuration key. It defaults to "simpleSAMLphp" if not set.

git-svn-id: https://simplesamlphp.googlecode.com/svn/trunk@667 44740490-163a-0410-bde0-09ae8108e29a