this prevents desktop clients from iq'ing use when they join

we don't want our own resource show up in the self contact

in some cases the the DNS query might take too long (even though we specified a timeout)
if that happens we need a secondary solution (besides killing the socket) to stop the thread

some devices might have problems contacting the IPv6 DNS server while in sleep mode

* start a new Conversations by pressing mod+space
* automatically start searching when pressing keys in StartConversationsActivity
* when hitting enter when number of search results == 1 open that conversation

fixes #1832