When Tempest is used in customer site, often we are required to
provide a testcase list including testcase names and descriptions.
Now no this kind of doc is available, so we can add descriptions
with the format of doc string for every testcase, so later we
can generata such a testcase description list.
There are hundreds of testcases missing descriptions, so we can
add them gradually, and limit the modified files in one patch
for the convenience of reviewing.
Change-Id: If14b4ec678355c850275ef38f9ed70cc0c877946
partially-implements: blueprint testcase-description
67b3d38934