Removed extra option parsing that was done in config class. It should be
as dumb as possible and not modify or create new configuration option
keys from existing ones.
Added exceptions to handle non-existing configuration or missing keys.
Aggregated all defaults in one place.
INI config is old, so switched from INIConfig to ConfigParser.
Change-Id: I73737221e371a1d164493b3de0a4a7bb2d9c5c3a