Import textproc/py-jsonrpclib-pelix from wip

This is a dependency of wip/electrum, with the goal of importing
wip/electrum later on.

This library is an implementation of the JSON-RPC specification.
It supports both the original 1.0 specification, as well as the
new (proposed) 2.0 spec, which includes batch submission, keyword
arguments, etc.

(js)