Enable docker on travis

.travis.yml

@@ -70,5 +70,8 @@
   "script": [
     "make -e $BUILD"
   ],
+  "services": [
+    "docker"
+  ],
   "sudo": true
 }

scripts/make_travisconf.py

@@ -12,6 +12,8 @@ cfg['dist'] = 'trusty'
 cfg['language'] = 'python'
 cfg['cache'] = 'pip'
 
+cfg['services'] = ['docker']
+
 cfg['git'] = {
     'submodules': False
 }