Slf 201412 minor fixups: a bit of everything

I've got a bit of everything here, including:

* gen_server:call() timeout tweaks
* changes to the value generator for sharing a single big block of random data
* add new key generators
* some new commands for the null driver, to aid debugging
* add socket_options to ibrowse (http raw driver)
* additional escript options

If these options are useful except get operation, it seems better to set them at `send_request/`.