separate tests according to the conditions they expect

[ThomasWaldmann]

some want (fake)root
some don't like (fake)root
some need fuse

tests should be dissected so only some few tests need to be run with fakeroot (the ones dealing with setting user, group or other stuff only root can do) and all other tests are happy also without fakeroot.

[ThomasWaldmann]

also: fakeroot slows down tests significantly and is not available everywhere.

[ThomasWaldmann]

hmm, this doubles matrix size: {py34,py35}-{fakeroot,normal}.