Remove escape characters from app paths.

[richburdon]

• App paths should not require escape chars (cleaner path, and required for PWAs: Fix path for PWA #67).
• We should also limit the allowable characters for the Registry name attribute to [a-z-_].
• NOTE: we need a valid delimiter other than @ for channels.

E.g., the following:

https://apollo1.kube.moon.dxos.network/app/wrn%3A%2F%2Fdxos%2Fapplication%2Fconsole%40alpha/#/apps

Should be:

https://apollo1.kube.moon.dxos.network/app/dxos/application/console/alpha/#/apps
``