WL-3332 - SES tool has wrong stylesheet

Copy development.css from 2.8 and the png it refers to
SAK-26240 download the actual CSS content from Github for cluetip 1.2.10

git-svn-id: https://source.sakaiproject.org/svn/reference/trunk@309646 66ffb92e-73f9-0310-93c1-f5514f145a0a
Merge pull request #24 from ox-it/3332

WL-3332 / SAK-26240