Emission

Changed
- Fixed some wrong entries in the database that caused a QGis plugin to crash (RoadEmissionCalculator)
- Bugfix in the calculator. For some CH4 emission calculations the end result will result in a 'ZeroDivisionError'. In that case a 0.0 value was supposed to be returned by the 'calculate' method.

Added
- Improved the readme file + cleanup

Added
- Included the sqlite db file in setup.py, so it will be part of python wheel package

Removed
- Removed annoying 'print' from planner.py

Added
- Added more required dependencies in the setup.py file. A fresh installation through pip will also install the required dependencies.

Added
- Major rewrite of the emission data included in this module. Went away from the JSON file and instead rewrote to use SQLite3 + sqlalchemy. Defined models for each table structure as well as util methods to properly lookup the correct emission for the vehicle choosen.

Changed
- Changed our "sqlalchemy" to use a "scoped_session" to work in a threaded environment if neccesary.
- Fixed minor bugs here and there.
- Efforts to ensure a Python2 compatibility, while still primarily focus on Python 3.
- Better error handling for issues with the remote webservice (a36c9c42ee33c967a4bd609cb78051f0486913d4)

Removed
- dependency for the EmissionJSONReader (will be removed at a later stage)