Updated Test Guidelines draft - 0701

Hi, all,
Here is the updated text for the Test Guidelines draft, incorporated
some of the input from the last teleconf (you'll need the css in the
style subfolder to color the Gd/Ck). 

Changes list:
- Fixed definitions of Checkpoint's priorities
- Fixed the glitch with the "Test Areas" guideline
- Added clarification to Ck 1.1, 1.2, 1.5 (removed "vague"), 1.6.
- added all the comments given on the last WG teleconf (except those
that are fixed) to the related places in the text, so that we can track
and remove them, as questions are resolved.
- added Dimitris's comment to the Gd.4 (about test framework).

Thanks