Add central configuration & spherical calculations & other stuff

[kerel-fs]

Major Changes:

• Add central configuration by python modules
• Rebase your commit "Add (slow) [radius, theta, phi] calculation"
• ogn/utils.py: Rename wgs84_to_sphere to haversine_distance
• Add scheduled task update_beacon_receiver_distance (the former update_receiver_childs function)

Your rebased commit already contains the pep8-fix (originally I wanted to rebase my PR on top of yours, but confused the branches, sorry).

An example for myconfig.py:

from config.default import *

# override database backend
SQLALCHEMY_DATABASE_URI = 'postgresql:///ogn'

[kerel-fs]

Closes #33 and closes #34.