ci: clone tests repo on jenkins_job_build.sh
ci: clone tests repo on jenkins_job_build.sh

If jenkins_job_build is called from other repository than
`tests`, the `tests` repo will not be in the $GOPATH tree and
the `manage_ctr_mgr,sh` call will not work. For that reason, we
need to clone tests repo using `go get`.

Fixes #914.

Signed-off-by: Salvador Fuentes <1643e95c8f87731315a493a18f5448396bacc6be@intel.com>

clearcontainers/tests,chavafg/tests,clearcontainers/tests,devimc/tests,chavafg/tests,devimc/tests