Also, add an auto-test for bootstrap and for LAN discovery.
Bootstrap is never tested otherwise, and LAN discovery is a prerequisite
for everything else. Having these two tests lets us rule out or identify
LAN discovery as a possible cause for test failures.
This way, developers compile toxcore, toxav, and toxencryptsave as C++ at
least once at home, reducing the likelyhood of running into travis
failures where we compile as C++ in the windows build.
