Implement get_service and get_services methods for K8sJujuConnector

- Add a new class (n2vc.kubectl.Kubectl) for managing the Kubectl commands
  - Add unit tests
- Add get_config_file() method for getting the path of the kubeconfig in K8sJujuConnector
- Implement get_service() and get_services() methods in K8sJujuConnector

Change-Id: I883ec21dad519c2dc65cb9bd601e539685336756
Signed-off-by: David Garcia <david.garcia@canonical.com>
diff --git a/requirements.txt b/requirements.txt
index 8cd901a..51a5faf 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -15,4 +15,5 @@
 git+https://osm.etsi.org/gerrit/osm/common.git#egg=osm-common
 juju==2.8.1
 paramiko
-pyasn1>=0.4.4
\ No newline at end of file
+pyasn1>=0.4.4
+kubernetes==10.0.1
\ No newline at end of file