Swagger Definition file: Allign to java swagger-codegen

When using the swagger-codegen with java client, more restriction apply.
It doesn't hanlde well module that starts with lower case, it does not
handle path parameter that is called "path", it doesn't support DateTime
and does not support object.

This patch changes our definition, with minimal impact on the actuall
code.

Signed-off-by: Amnon Heiman <amnon@cloudius-systems.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>