STS-3513: create dashboard landing page
STS-3513: tweaks to Dashboard and landing page

  - Add a optional close button to tabs.

  - Landing page opens webpages in dashboard instead of
    Eclipse internal web browser

  - Use CSS mediaqueries to make landing page look ok 
     on smaller screen

  - Read a properties file to allow customizing tab labels
    for certain urls.
STS-3513: Dashboard and landing page cleanups

Comment out all code related to preferences page.
May or may not be useful in near future. For now its not
in use anymore make this clear by commenting it all out.