Refactored the handling of colors to set them earlier

This ensures that the colors setting is taken into account even when an
exception occurs during the config parsing.
Fixes #509
Added a few missing --no-colors options in the testsuite

This allows these scenarios to pass on Windows where the autodetection in
child process will not always disable colors automatically, given the
environment variables are forwarded.
Merge pull request #513 from stof/color_support

Fixed the color handling for early exceptions