Add an EventLogger interface to allow apps to get a log of the request timeline
Add QueryLogger interface to allow apps to get a list of used queries
Activate the query logger on connect
Rename namespace to Diagnostics
Log some basic events
Rename to NullQueryLogger
Allow adding events that hapend before the event logger was loaded
Log some additional events
call initPaths() right before the server is instantiated
Merge pull request #11416 from owncloud/eventlogger

Allow apps to gather performance diagnistics