vcs: Skip error handling in case of responses from VCSMiddleware.

vcs: Add a flag to the environ to skip the error handling for responses from VCSMiddleware

config: Use settings from pyramid app init for appenlight.

config: Sanitize 'appenlight' and 'gzip_responses' settings.

config: Set 'gzip_responses' to false by default.

config: Remove unsused setting 'full_stack' from ini files.

config: Move appenlight wrapping from pylons to pyramid.

ae: Rely on fully prepared settings in appenlight wrapping function.

tests: Add test to check the sanitize settings method in app init.

tests: Adapt tests to recent changes.