[PyOpenSSL branch]

- Close connection after creating account. Fixes #2676
- Handle normal connection close by server. Fixes #2671
- Do not disconnect if we haven't received starttag yet. Fixes #2668. Fixes unticketed bug causing account creation not to work with PyOpenSSL and asynchronous handshake (see also #2671). Behaviour of #2634 is also improved but now results in deadlock.