Also, implement the ability to configure an alternate key store
file location. This permits the running of unit tests without
clobbering the live key store file.
Also, add a test to confirm that the key store file is being written
out and reread correctly.
Right now we happily accept every certificate in our local key store as long as
the hostname matches the certificate DN. So this test fails.
It's not a huge deal since the user accepted the certificate at one point. But we
want to do this right.
