adding configurable flag omero.web.webstart_curators_only to maintain access to webstart
display message if webstart is not avaialble
removing error message from the toolbar
renaming setting to WEBSTART_ADMINS_ONLY
unifying insight_url and preserving context
adding custom decorator for webstart
Merge pull request #2244 from aleksandra-tarkowska/webstart_access_limited

Webstart access limited