general config: Don't keep unused configuration directives
IcingaCommand: Fix strict standards violation: Only variables should be passed by reference
File: Fix ErrorException::__construct()'s parameters
Throw an ErrorException on E_STRICT errors
Fix our Logger not supporting named logging levels and requiring the 'enabled' directive
Logger/FileWriter: Rename 'target' directive to 'file'
Logger/SyslogWriter: Define configuration defaults here

Usage of closelog() is optional so I removed the explicit calls.
Logger: Fix the StreamWriterTest
CLI: Fix logging setup
Bootstrap: Remove logging configuration directives which do not override defaults
logging config: Support 'log' 'none'