Migrate travis to container-based infra

We hope it will avoid OutOfMemory issues when building gerrit.

Change-Id: I93d1aff0a300f263cad282d5ba321cbd6672f1d4
diff --git a/.travis.yml b/.travis.yml
index 4baa578..ddabe77 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -14,8 +14,14 @@
 
 language: java
 
-before_install:
-  - sudo apt-get install automake autoconf autogen
+sudo: false
+
+addons:
+  apt:
+    pakages:
+    - automake
+    - autoconf
+    - autogen
 
 install:
   - cd ../..