use flask restplus for swagger documentation
improve headers swagger doc
remove calls to jsonify when using restful

reason: when using Flask-RestFul (via inheritance of Resource), a dict
will automatically be jsonified
add Headers model for swagger doc
add swagger to lookup view

Also, the arbitrary query string arguments are now ignored, instead of
passed down to the service. Reason: impossible to parse, and not
necessarily a good method for passing arguments.
Merge pull request #2 from xivo-pbx/5027-dird-swagger

5027 dird swagger