Check if user is already logged in for DAV auth, instead of logging in and creating new sessions for every request

autotest.sh added: create an fresh environment using sqlite (mysql anf pg will follow) and executes the test suite

restructuring test suite invocation - now we load all test cases into one suite and execute this single suite. this is necessary to be able to generate one xml report and is also a precondition for code coverage analysis(which will follow soon)

update routine implemented
version number of files_versions increased

Conflicts:

	apps/files_versions/lib/hooks.php