update docker search to reflect future changes of the api

I removed `APISearch`, the docker daemon serves as a proxy in that case, so I use the struct from the registry package.

    $ docker search kencochrane
    Found 2 results matching your query ("kencochrane")
    NAME                    DESCRIPTION         STARS               OFFICIAL            TRUSTED BUILD
    kencochrane/testrepo                        0                                       [OK]
    kencochrane/testrepo2                       1                                       [OK]