Altered constructor, two more parameters. Fixed kwargs.iteritems. Added ...

Added two more parameters to constructor. app_key and user_key can be used to configure the script directly, without use of configuration file.

Changed kwarks iteration for python 3.

Tests pass using python 2.7.
Tests do not pass using python 3.4 . Given assertion `assert(instance.message=="No valid configuration found")` does not work