Minor fixes to envsubst for webapps. Somewhat specially treated is `LACONIC_HOSTED_CONFIG_homepage` which can be used to replace the homepage in package.json. With react, this gets an extra `/` though, which we need to remove.
Reviewed-on: cerc-io/stack-orchestrator#746
Co-authored-by: Thomas E Lackey <telackey@bozemanpass.com>
Co-committed-by: Thomas E Lackey <telackey@bozemanpass.com>
