Start drafting data modeling for peers

This also adds a function, which should serve as a starting point to
parse "compact" peer strings from tracker announce responses.
Start drafting data modeling for trackers

This adds a base function for announce queries, as well parsing of the
announce responses.  The most fragile concept for our current drafts is
how state is going to be handled and passed around.
Expose recently added modules

Adds entries to `exposed-modules`.