* Rename and split http_source feature to http and https
* Enable http sources when using processed asset mode
* Fix ureq/rustls feature gate (it was only working by accident because ureq with full features is part of the dev dependencies)
* Disable gzip and json ureq features
* Misc. rewording of a couple docs
* Setup HttpSourcePlugin as part of DefaultPlugins to allow for future configuration (there is currently none)