2.1.0 release

• Move most of the logic to a Processor class which does not depend on the composer event and package. Ref #30
• Add the support of existing empty file for Capifony compatibility
• Add the support of multiple managed files
• Preserve other top-level keys than the configured one in the file
• Add a rename map used to rename parameters when updating the parameters file
• Add the possibility to use another top-level key than parameters