[YSM] Edge case - allow double quoted arrays

[jrushlow]

This potential issue came to light from issue #777 with failing test cases in WIP PR #782

In the bulk of Symfony - yaml uses single quotes ' for array values. However in docker yaml files, double quotes " are the standard. Docker is the only edge case I can think of where allowing this would make sense and keep things consistent. As such, if we allowed double quotes, it should only be as a result of calling make:docker:database. But that command will soon be deprecated (see the discussion in #777 for further details).

Should we change YamlSourceManipulator to allow double quotes in array values?
If we do, should this be limited to docker related yaml files?