[Design] Updated dashboard spec

[Sheila Mooney]

I updated the dashboard spec...

http://svn.osafoundation.org/docs/trunk/docs/specs/rel0_7/ 
Dashboard-0.7.html

+ We have split the work for Alpha4 into 3 iterations: first, later,  
could be deferred and added 3 visuals of what it would look like  
after each phase (have already discussed this with Bryan).
+ Added a couple of clarifications around the date column based on a  
conversation on the list.
+ Fixed a few typos.