* [REST] New API for conversion between file format and JSON
Related to #4585
This PR supports conversion of things and items.
It supports DSL and YAML file formats.
A first new API (POST /file-format/create) allows to create a file format (DSL or YAML) from a JSON object.
A second new API (POST /file-format/parse) allows to parse a file format (DSL or YAML) to a JSON object.
These 2 APIs should help Main UI displaying DSL and YAML file formats for things.
Signed-off-by: Laurent Garnier <lg.hc@free.fr>