add base_url and service_url to app

base_url communicates the base URL of the application to the page
using the `<base>` tag. With this change the extension can render
the app template into the extension bundle and ensure that the
extension still knows the base URL for the live application.

service_url is mainly added to get more logic out of the template
and let the app pass it in.
add paste and pastedeploy to req
consistent use of font sizing tricks
scroll can be auto on the sliding panels
remove unnecessary units
some list padding on the front page instructions