Fix #76: Block outgoing stanzas to blocked users

Signed-off-by: Daniele Ricci <daniele.athome@gmail.com>
Fix subscriptions stored JID

Signed-off-by: Daniele Ricci <daniele.athome@gmail.com>
A unit test for resolver subscriptions

This is the very first unit test for Kontalk XMPP server code. Many
others will follow soon.

Signed-off-by: Daniele Ricci <daniele.athome@gmail.com>