Partial conversion of some subprocesses to modules

Fixes #16 (closed)

The two non-postscripts in bin/ have been moved into src/rapidpe_rift_pipe where they are to be used as modules, rather than called as subprocesses. This means we can pass Python objects to them, rather than just command line arguments (i.e., strings), so we now pass the already-parsed Config object, as well as a dictionary that doesn't need to be communicated via JSON.

cli.py has been modified to work with this change for both scripts.

config.Config now records the config file's path as an attribute, which was necessary for this module.

Note that create_submit_at_exact_signal_position crashes when used, but the crash happens in the same place as it does before this edit.