Http Server: Split Testing into multiple files

This split the API testing to multiple files. In the testing directory
there is an api directory equivalent to the api directory under the
httpserver.

There should be an test{api-name}.py file in the api for each api.
Each api inherit from basetest.Basetest and gets all the API
functionality from the base class.

All test files under the api directory are picked automatically.

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