You can try this:
Go to : /usr/share/meteor/bundle/programs/web.browser
You will see "head.html" & another '.js' file. I think the name of the JS file is auto generated. So, name will be different in each installation.
Open "head.html" file & you can change the title value from "BBB - HTML5 Client" to anything :P
Now open ".js" file & search for
Meteor.settings.public.app.copyright
replace that text using your desirer value. Don't forget to use double quotation. Like:
That's all. Save the files & clean your browser cache before reload. Enjoy :)