Adapt the HTTP tests to new API

[johannesduesing]

Describe the problem
Since we specified a new HTTP API for the registry (see #57), which is currently being implemented, we also have to adapt the entire HTTP tests to the new URI schemas.

Describe the solution you would like
Adapt the existing tests. The functionality will stay the same, only the uri and parameter format will need to be changed.

[24santoshr]

Referring #90

[johannesduesing]

Closed with #90