javelin: fix object destruction

When adding "destroy" support in javelin, a wrong condition has been
introduced to validate if an object has been destroyed or not by its
HTTP return code.

204 is returned and was considered as an error, which is wrong.
Also, delete a resource cleanup dupplication (servers).

Change-Id: I1adaf143ebf2de90d1b2cafc91dcd3a521b96fec
Signed-off-by: Emilien Macchi <emilien.macchi@enovance.com>
Merge "javelin: fix object destruction"