change top bar
add new nav links
add target=_blanks
Merge pull request #819 from drwelby/804-topbar

804 topbar
Update and rename README to README.md
finish up orphaned table/layers cleanup script
adjust announcements - allow safe content

and remove link to superfluous page and make date font smaller
Merge branch 'master' into iss-803-askbot-widget
askbot widget, follow up to @e10cc26, refs #803

remove tooltip 'search or ask your question' div
adjust height to prevent scrollbar