Spell TestCase.teardown correctly as tearDown().
Spell TestCase.teardown correctly as tearDown().

So that it is invoked by test framework and the tmp filesystems are
actually unmounted and their temporary directories deleted.

Signed-off-by: mulhern <7b51bcf507bcd7afb72bf8663752c0ddbeb517f6@redhat.com>

rvykydal/blivet,rhinstaller/blivet,vpodzime/blivet,AdamWill/blivet,vojtechtrefny/blivet,rvykydal/blivet,vpodzime/blivet,jkonecny12/blivet,jkonecny12/blivet,dwlehman/blivet,vojtechtrefny/blivet,dwlehman/blivet,AdamWill/blivet,rhinstaller/blivet