Consider replacing com.canonical.Oxide with Oxide.Ubuntu

[Chris Coulson]

At the moment, Oxide.Ubuntu depdends on com.canonical.Oxide, and the types it registers are prefixed with "Ubuntu" (eg, UbuntuWebView). I wonder whether we should actually use it to replace com.canonical.Oxide entirely, so that it registers all of the existing QML types. This would mean we could drop the "Ubuntu" prefix from new types and just call the new webview "WebView"