[plugins] director: dead code cleanup
[plugins] director: (spaces)
[plugins] director: coding style: favor override over virtual
[plugins] director: dead code cleanup
[plugins] director: use unique_ptr<> for http backend socket
[http] HttpConnection: implicitely protect posting into the connection I/O worker by ref()/unref() against deletions in the middle
[http] HttpRequest: eliminate unnecessary post()-indirection inside writeCallback()
[plugins] director: major code refactorization of the HTTP backend implemenation in order to void reference counts.