Allow the caller to override the logger used.

We already have a logger associated with the client, and this makes it
easier to track which client is doing what when the logs are aggregated
on a log server.
Reduce log verbosity by making individual lines more useful

This makes it easier to match requests and responses when the logs are
aggregated on a log server.
Split debug logging into multiple loglevels

The getEffectiveLevel check is not actually necessary, the logger
already performs an isEnabledFor check when you use the
loglevel-specific methods (see Logger in python's logging module).

This also breaks DEBUG into two levels, INFO (for the request-response
cycle) and DEBUG (for the protocol-specific messages and pings).
Fixed sequential znode creation so that it is possible to create sequences without a prefix by passing a trailing slash in the path.
Simplified passing the trailing flag if creating a sequential znode.
moving imports to top of module

based on email threads showing excessive GIL lock time and deadlocks
when doing extensive imports not at module load time
Merge pull request #105 from heckj/importchange

moving imports to top of module to avoid import lock errors (maybe due to threading?)
keep changelog up-to-date
disable travis-ci email spam, it's not reliable enough :(
Merge pull request #85 from novas0x2a/logging

Increase information density of logs
- Issue #99: Better exception raised when the writer fails to close. A
  WriterNotClosedException that inherits from KazooException is now raised
  when the writer fails to close in time.
Merge pull request #103 from ryanuber/prefixless_sequential_znodes

Prefixless sequential znodes
change log update for #103.
make it easier to tell where a traceback came from

log.exception already loads the exc_info, so there's no need to pass it
into the exception method; instead, use the message to indicate where
the exception was detected.
Merge pull request #100 from novas0x2a/traceback

make it easier to tell where a traceback came from
- Issue #62, #92, #89, #101, #102: Allow KazooRetry to have a
  max deadline, transition properly when connection fails to LOST, and
  setup separate connection retry behavior from client command retry
  behavior. Patches by Mike Lundy.
Merge branch 'master' of github.com:python-zk/kazoo

Conflicts:
	kazoo/protocol/connection.py
Remove python 2.7-ism.
some small doc tweaks
pep8