Add Using SSLv3 to Pitfalls

Users should not be using SSLv3 on their nginx servers, due to the design flaws found and shown in the POODLE vulnerability.  We may want to add the use of SSLv3 protocols as a pitfall and something that you just should not ever do.
Rewrite to 80-char line limit

Oopsies!
Remove double space.

Again, high school education messed with me... another accident is added as a result.
Merge pull request #13 from teward/patch-1

Add "Using SSLv3" to Pitfalls