This is a maintainance release - bugfixes and upgrades of dependencies.

This release fixes a major issue with leaking file descriptors. Please
upgrade as soon as possible. Ruby 2.1 is required - no other upgrade
issues are known.

bugfixes:
 * #3 handle domains without A-record
 * filedescriptor leak from http_adapters
 * send empty json object on 404 rather than nil
 * remote nicknym is on port 6425
 * use user:password@ prefix in http basic auth

upgrades:
 * require at least ruby 2.1
 * upgrade bundled gems to latest available

tests:
 * more meaningful error messages in case of failures
 * test bundle is up to date
 * regression test for nonexisting domain

integration:
 * Add systemd service unit file
 * Restart nickserver automatically from systemd
 * gitignore: bundle dir

cleanup:
 * old empty adapters and tests

If a domain only has an mx record but no A record it
will trigger a ConnectionError when attempting the
nicknym key lookup.

We need to detect and handle this in the http adapter
already because once the exception is handled by Celluloid
our actor will be terminated.

So now we allow for handing a rescue option to the
adapter with a string that is checked for inclusion in
the error message. If the string is found the exception
will be caught and the adapter returns nil.

We only make use of this when checking the availability
of nicknym so far. That should be the only http request
going out.

Now we reuse a single adapter for all requests triggered
by an incoming request. Then we .terminate the adapter.

Includes a regression test.

sending nothing was keeping the connection alive.

We may use a different port in the config that is then mapped somehow.
But this should not affect where we try to contact remote nicknym servers.

This will get us more debug info in the logs if it happens again

http.rb does not do this on its own.

Allow queries by fingerprint (using keyservers to reply) and support key
lookup from other nickservers.

This is a major rewrite both in terms of our dependencies and our
architecture.  We moved the server and http_client from eventmachine to
Celluloid based libraries. This allows for a more concise syntax and
proper https handling.

In addition we now support ruby 2.3, use a Logger instead of stdout and handle
network errors properly

Turns out without this nickserver will not respond to multiple concurrent requests.