Update README.md's ChatManager example to new API
Refactoring: All connection classes begin with XMPP now

This commit renames classes as follows:
 * TCPConnection --> XMPPTCPConnection
 * BOSHConnection --> XMPPBOSHConnection

There are two reasons for this rename. First, it is there to indicate
that the classes actually _are_ XMPP connections, using different
transport mechanisms. Second, it makes auto-completion in IDEs easier,
the developer can type XMPP<complete> and choose the right backend.
VCardProvider should treat tel code element optional

SMACK-555
Remove star imports in VCardProvider
Return Collections (or sublcasses) instead of Iterators

This allows us to exploid Java 8 streams and Java 5 for-each
loops. The returned Collections are usually unmodifiable. We decided
against returning Iterable because this would mean determining the
size in O(n) compared to Collection.size() which is often faster
(e.g. O(1)).