Add tox and travis config file, update .gitnore.
Avoid raising None on failed set_keyspace

If the connection was already defunct when the set_keyspace
call failed, None would be raised, resulting in a TypeError.
Hold deque lock when popping in asyncore

In multithreaded environments, this could result in corruption of the
deque, leading to malformed messages.

Additionally, this change attempts multiple writes whenever select()
reports that the FD is available for writing, similar to what is already
done for libev.
More control conn debug logs on startup
Optimize NTS replica map building

In the case where one DC used vnodes and the other did not, the previous
algorithm hit a worst-case of O(n^2) on the number of tokens.
New large data tests
Adjust row_factories within create_schema method. Use a longer timeout for wide_tables test.
Only build token replica map as needed
Minor PEP-8 fixes
Row format is dict, not namedtuple for schema refresh
Handle dropped keyspaces correctly
Don't make ks recreate test incredibly long
Close conns in trash on shutdown
Remove __del__ from Connection subclasses
Avoid double erroring of callbacks

Under certain conditions, when a connection was closed by the server,
the close() method would first be called, followed by the defunct()
method shortly afterwards.  Both of these would error out all callbacks.

This avoids doing "defunct" work if the connection is already closed,
and holds a lock to avoid any other race conditions which might result
in erroring all callbacks twice.
Ensure in_flight is decremented when ops time out

Internal operations, such as control connection queries and preparing of
statements, use a different method for synchronously executing queries.
If those timed out, the in_flight count for the relevant connection
would not be decremented, leaving the connection to appear more busy
than it actually was.
Actually add NullHandler in logging to cassandra

For some reason this was commented out duing the initial implementation
Handle missing/unrecognized replication strategy
Use efficient bulk writing
wide-row fix