Adding initial support for gitlab runner integration testing.

added the robot keytab, now testing that it can authenticate. 

.gitlab-ci.yml

 stages:
   - build
   - test
+  - integration
 
 # -- build ------------------
 .build: &build
@@ -95,6 +96,35 @@ test:python3.7:
   <<: *test
   image: python:3.7
 
+# -- test -------------------
+.integration: &integration_test
+  stage: integration
+  image: python
+  script:
+    - echo "${ROBOT_KEYTAB}" | base64 -d | install -m 0600 /dev/stdin keytab
+    - apt-get update && apt-get install -y curl krb5-user xsltproc
+    - PRINCIPAL=$(klist -k keytab | head -n 4 | tail -n 1 | sed -E 's/^.* +//')
+    - kinit $PRINCIPAL -k -t keytab
+    - rm keytab
+    - ./scripts/ligo-proxy-init -k
+    - curl -E /tmp/x509up_u${UID} https://gracedb-test.ligo.org/api/user-info/
+
+integration:python2.7:
+  <<: *integration_test
+  image: python:2.7
+
+integration:python3.5:
+  <<: *integration_test
+  image: python:3.5
+
+integration:python3.6:
+  <<: *integration_test
+  image: python:3.6
+
+integration:python3.7:
+  <<: *integration_test
+  image: python:3.7
+
 # -- docs -------------------
 # Although we don't host the docs on Gitlab Pages,
 # we still want to check that they build properly.