DATAMONGO-1824 - Switch to TravisCI-provided MongoDB service.

Original pull request: #521.

.travis.yml

@@ -6,6 +6,9 @@ jdk:
 before_script:
   - mongod --version
 
+services:
+  - mongodb
+
 env:
   matrix:
     - PROFILE=ci
@@ -23,9 +26,7 @@ env:
 addons:
   apt:
     sources:
-      - mongodb-upstart
+      - mongodb-3.4-precise
-      - sourceline: 'deb [arch=amd64] http://repo.mongodb.org/apt/ubuntu precise/mongodb-org/3.4 multiverse'
-        key_url: 'https://www.mongodb.org/static/pgp/server-3.4.asc'
     packages:
     - mongodb-org-server
     - mongodb-org-shell
@@ -37,6 +38,8 @@ cache:
   directories:
     - $HOME/.m2
 
-install: true
+install:
+  - |-
+    mongo admin --eval  "db.adminCommand({setFeatureCompatibilityVersion: '3.4'});"
 
 script: "mvn clean dependency:list test -P${PROFILE} -Dsort"