Update submodules: plugins (new commits)

plugins:
    8c88b5c Chris Smith <chris@dmdirc.com>
            Tidy the logging plugin.

            Gerrit: http://gerrit.dmdirc.com/3845

Change-Id: Ic1e9e74dd6cc5566f942b1ea9e637e1ac0807a02
Update submodules: plugins (new commits)

plugins:
    3ed98dd Chris Smith <chris@dmdirc.com>
            Tidy various plugins.

            In particular make the DNS plugin use the DNS dagger module, not
            the debug module. Testing++.

            Gerrit: http://gerrit.dmdirc.com/3846

Change-Id: I87d07b068732adde48576e0f3f0956f2ea0aaec7