Also refactored the likes/liked add-to-collections logic so that they
are also applicable for following and followers collections. This code
is still as ugly as sin.
Before more tests are to be written, the delivererPool concept needs to
be fully divorced out of the fed library. It is a detail that is
tangential but supplementary. Right now though it is complicating the
tests due to its asynchronous & complex nature. Breaking it out
will simplify the ~90 tests remaining that capture the more nuanced
behavior of this implementation.
