support multi-module packages

[casperdcl]

server:

zerorpc --server --bind ipc:///tmp/os os

client:

zerorpc ipc:///tmp/os path.join one two  # error

The only workaround right now seems to be having a separate server zerorpc --server --bind ipc:///tmp/os_path os.path and using zerorpc ipc:///tmp/os_path join one two

[bombela]

Serving a module via the zeropc cli tool is targeted to modules designed for being exposed on the network. In this case, you really expose all public functions in a single module. If you want to expose anything else, write a python script that gathers all the functions you want, and start a zerorpc.Server with it. Looks at how the zerorpc cli does it as a source of inspiration.