tests: use ts_check_losetup in losetup test

In losetup test we have to handle the special case that ts_check_losetup
requires a working losetup binary.

Signed-off-by: Ruediger Meier <ruediger.meier@ga-group.nl>
tests: ts_device_init requires loop support

Signed-off-by: Ruediger Meier <ruediger.meier@ga-group.nl>
tests: some more tests need loop support

Signed-off-by: Ruediger Meier <ruediger.meier@ga-group.nl>
tests: ts_scsi_debug_init must not run in a subshell

ts_skip and ts_die won't work from subshell. Now we simply use
DEVICE which is still globally set in that function.

Signed-off-by: Ruediger Meier <ruediger.meier@ga-group.nl>
tests: cleanup ts_scsi_debug_init

Sort out global and local vars. We still keep DEVICE global,
see previous commit.
Skip really quiet if modprobe fails.

Signed-off-by: Ruediger Meier <ruediger.meier@ga-group.nl>
tests: introduce TS_CMD_UUIDGEN (never use installed one)

Signed-off-by: Ruediger Meier <ruediger.meier@ga-group.nl>
travis-ci: minor cleanup and speedup

Signed-off-by: Ruediger Meier <ruediger.meier@ga-group.nl>
travis-ci: enable root checks

Signed-off-by: Ruediger Meier <ruediger.meier@ga-group.nl>
tests: fix "KNOWN FAILED" for subtests

It didn't worked for tests with subtests.

Here we consolidate both cases which fixes the issue by the way. This
is basically a rewrite of 7641ccec.

Signed-off-by: Ruediger Meier <ruediger.meier@ga-group.nl>
tests: fix hexdump, add ts_finalize

Signed-off-by: Ruediger Meier <ruediger.meier@ga-group.nl>