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

test: regression test for nonexisting domain

See merge request !17

related to platform#8674

test: minor: add http adapter test

See merge request !16

fix: #3 handle domains without A-record

Closes #3

See merge request !15

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.

minor: tweak file descriptor count test

See merge request !14

Upgrade/bundle

See merge request !12