LU-160 Split small/big file parts of test_155_load

LU-160 Split small/big file parts of test_155_load

Separate the small file parts and the big file parts of test_155_load
into different tests. This has the benefit of always running the small
file portions of test 155, even if the big file tests are skipped.

Signed-off-by: Prakash Surya <surya1@llnl.gov>
Change-Id: Ic895fb8590f1d15fbd1889b64b0a6143ff1c6289
Reviewed-on: http://review.whamcloud.com/528
Tested-by: Hudson
Reviewed-by: Yu Jian <yujian@whamcloud.com>
Reviewed-by: Chris Gearing <chris@whamcloud.com>
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>