activate the layout discovery during tests

default is disabled to keep settings consistent with or without
flexisettings.
change contributors file to ascii format
add debugging instructions in readme file
get layout discovery to use configurable names

folder names to look for in the different paths are now set through
`FLEXI_*` configuration variables.
add documentation for more flexisettings defaults
add __doc__ to all the methods
rename FLEXI_TEMPLATES_FOLDERS to FLEXI_TEMPLATE_FOLDERS
add autoreload feature to work with django

in the process, `FlexiSettingsProxy._wrapped_modules` is now a dict.

Closes #5