CI: here we go again install-ing manually

Author: kares

.travis.yml

@@ -1,8 +1,12 @@
 import:
 - logstash-plugins/.ci:travis/[email protected]
 
-services:
-  - redis
+addons:
+  apt:
+    sources:
+      - sourceline: 'ppa:chris-lea/redis-server'
+    packages:
+      - redis-server
 
 #before_install: # Redis tried to bind to ::1 but IPv6 isn't supported
 #  - sudo service redis-server stop || true