Move HTTPURLConnection to Scala
Remove `pragma: no-cache` in request
Minor: Comment, indent
Use Apache HTTP Client for embedding/proxying

- refactor HTTPURLConnection
- HTTP client handles gzip compression
- improve proxying of headers
- add charset to text/css for aggregated resources
- persistence proxy: close stream
- move Credentials to http package
- embedding servlet filter supports HTTP client configuration
- proxy portlet supports HTTP client configuration
- move some tests
- fix indentation
Small changes to Actions dialog

- rename instance
- move init code
- hide set service values if no service of type is available