Signed-off-by: NLucas Meneghel Rodrigues <lmr@redhat.com>

We want avocado tests to not require specific directories,
the user should be able to arrange them in the dir structure
they see fit. Also, if a test requires data, we suppose their
data dir is located in the same directory as the source file,
with the name:

[modulename].data

Re arrange the test dir to reflect this new structure.
Signed-off-by: NLucas Meneghel Rodrigues <lmr@redhat.com>

Signed-off-by: NCleber Rosa <crosa@redhat.com>

Add a new test that exercises the test whiteboard.

When run multiplexed, it writes both simple text and binary random
data, in different sizes and number of writes.
Signed-off-by: NCleber Rosa <crosa@redhat.com>