TODO handshake for NodeLink to first check protocol versions

* master: (23 commits)
  Make the identification of the primary master easier with 'neoctl print node'
  client: fix AttributeError when connected to a master that happens to be secondary
  qa: speed up SQlite tests by accessing DBs in unsafe mode (e.g. no sync)
  master: fix identification of unknown masters
  Better logging of connector errors
  qa: relax assertion in testDeadlockAvoidanceBeforeInvolvingAnotherNode
  client: fix possible data corruption after conflict resolutions with replicas
  qa: new --readable-tid runner option
  qa: make Patch work on functions
  qa: new --continue-on-success and --stop-on-success runner options
  doc: add advice about the number of master nodes to set up
  Improvements to --dynamic-master-list
  Make NodeManager.remove stricter
  Clean up neo.lib.protocol
  Use ProtocolError instead of Notify for unexpected answers, and drop Notify
  Rename node states: DOWN -> UNKNOWN, TEMPORARILY_DOWN -> DOWN
  Remove UNKNOWN node state
  Reimplement election (of the primary master)
  Use existing generic way to ignore AcceptIdentification on closed connections
  Remove BROKEN node state
  ...

Now, the primary master is the running master with None displayed in the
last column. Before, it could be the id timestamp of when it was secondary,
which was obsolete information.

This fixes up commit 23b6a66a,
which reimplements election.

  poll raised, retrying
  Traceback (most recent call last):
    ...
    File "neo/client/handlers/master.py", line 41, in notPrimaryMaster
      super(PrimaryNotificationsHandler, self).notPrimaryMaster(*args)
    File "neo/lib/handler.py", line 157, in notPrimaryMaster
      assert primary != self.app.server
    File "neo/client/app.py", line 109, in __getattr__
      return self.__getattribute__(attr)
  AttributeError: 'Application' object has no attribute 'server'

This fixes the following crash:

  Traceback (most recent call last):
    ...
    File "neo/master/handlers/identification.py", line 94, in requestIdentification
      uuid = app.getNewUUID(uuid, address, node_type)
    File "neo/master/app.py", line 449, in getNewUUID
      assert uuid != self.uuid
  AssertionError

This really fixes the bug described in
commit 40bac312,
which could probably be reverted. It only reduced the probability of failure.

What happened is that the second conflict on 'a' for t3 what first reported by
an answer to first store with:
- a base serial at which a=0
- a conflict serial at which a=7
However, the cached data is not 8 anymore but 12, since a second store already
occurred after the first conflict (reported by the other storage node).

When this conflict was resolved before receiving the conflict for second store,
it gave:

  resolve(old=0, saved=7, new=12) -> 19

instead of:

  resolve(old=4, saved=7, new=12) -> 15

(if we still had the data of the first store, we could also do
  resolve(old=0, saved=7, new=8)
 but that would be inefficient from a memory point of view)

The bug was difficult to reproduce. testNotifyReplicated had to be run many
many times before that race conditions trigger it. The test was changed to
enforce some of them, and the above scenario now happens almost always.