Define version in setup.py instead of importing from __version__.
Update requirements in setup.py.
Fix wrong variable name.
Fix wrong log format.

This caused 'not enough arguments for format string' errors.

This also fixed github issue #5.
Fix: backend flickr_storage must not set global log level to debug.
No longer inherit log.Loggable from logging.Logger.

Loggable uses the delegation pattern, not the subclass.
Let (un)subscribe get the logger once instead on each use.
In log, reexport only required symbols from logging.

The only symbol required from std-module logging is `getLogger`.
Get logger only once per instance.

Unfortunately Loggable.__init__() is not called by each subclass
of Loggable. Thus we need to check if the logger is already set in
each logging method.
Remove now unused module coherence.extern.logger.
Change  format of log message to be less spaces and more concise.

- Move time to the front.
- Remove aligning spaces after logger-name.
Implement a Logger class to get the correct stack frame of the caller.

Without this hack/work-around, all log messages will look like
coming from module coherence.log.
Fix: ServiceControl must be subclass log log.Loggable.

Since ServiceControl ist using log methods.
Fix logging format strings everywhere.

The old log-system took any number of strings, logging one behind another.
In contrast the std-lib logging module takes a format string. This
change fixes the format strings by appending a ' %s' for every argument.

This changes have been applied to all python files using fix
logging_format_string from https://github.com/htgoebel/pep8ify (branch
coherence-project) and the result has been checked.

Additionally a few places have been changed manually.
Remove '%' string formatting in logging everywhere.

This changes have been applied to all python files using fix
logging_mod_operator from https://github.com/htgoebel/pep8ify (branch
coherence-project) and the result has been checked.

Additionally a few places have been changed manually.
pep8: Add trailing newline and remove trailing blank lines.

This changes have been applied to all python files using fixes
missing_newline and trailing_blank_lines from
from https://github.com/htgoebel/pep8ify and the result has been checked.
pep8: Remove trailing whitespace

This changes have been applied to all python files using fix
missing_whitespace
from https://github.com/htgoebel/pep8ify and the result has been checked.
pep8: Whitespace before inline comments.

This changes have been applied to all python files using fix
whitespace_before_inline_comment from
from https://github.com/htgoebel/pep8ify and the result has been checked.
pep8: Avoid extraneous whitespace before open parenthesis.

This changes have been applied to all python files using fixes
whitespace_before_parameters from
from https://github.com/htgoebel/pep8ify and the result has been checked.
pep8: Fix whitespace around operators.

This changes have been applied to all python files using fixes
whitespace_around_operator from
from https://github.com/htgoebel/pep8ify and the result has been checked.