LU-1187 tests: Add parallel sanity tests to dne

1. Add parallel sanity tests(dne_sanity) to run sanity
tests on different directories at the same time.

2. Add PARALLEL check line in sanity to skip some tests which
are unable to run parallel.

3. Do not check multiop in run_one when multiple sanity
is running.

4. In test_105, replace DIR with MOUNT to check flock option.

Test-Parameters: envdefinitions=SLOW=yes testlist=sanity,dne_sanity
Signed-off-by: Wang Di <di.wang@whamcloud.com>
Change-Id: If2386e5465c2067059fb72c5fc95ac690ddd3fa4
Reviewed-on: http://review.whamcloud.com/4318
Tested-by: Hudson
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Jian Yu <jian.yu@intel.com>