Fixes Python3 support and improves formatting

[JFF-Bohdan]

Fixes issues with Python3 support

• wrong string encoding/decoding;
• wrong navigation through dictionaries

Improves formatting and Python3 syntax support:

• all strings unicode by default, all u" removed;
• formatting improved using flake8 linter (configuration file added).

Adds conditional import

• __init__.py now conditionally includes needful files.

Warning! Tests still broken!

http://lucumr.pocoo.org/2014/1/5/unicode-in-2-and-3/

The main difference between Python 2 and Python 3 is the basic types that exist to deal with texts and bytes. On Python 3 we have one text type: str which holds Unicode data and two byte types bytes and bytearray.

[viplifes]

Thanks!