use mock for search

Docker-DCO-1.1-Signed-off-by: Victor Vieux <victor.vieux@docker.com> (github: vieux)
Move server and buildfile into server pkg
Docker-DCO-1.1-Signed-off-by: Michael Crosby <michael@crosbymichael.com> (github: crosbymichael)
Update integration tests for server pkg
Docker-DCO-1.1-Signed-off-by: Michael Crosby <michael@crosbymichael.com> (github: crosbymichael)
Merge pull request #4593 from crosbymichael/move-server

Move server and buildfile into server pkg
Merge pull request #4647 from vieux/fix_registry_tests

use mock for search