Backport travis.yml from master / php7 branch

Author: sodabrew

.travis.yml

@@ -1,27 +1,33 @@
+sudo: required
+dist: trusty
+
 language: php
 php:
     - 5.5
-    #- 5.4
-    #- 5.3
+    - 5.6
+
 env:
-    - LIBMEMCACHED_VERSION=1.0.17
-    - LIBMEMCACHED_VERSION=1.0.16
-    - LIBMEMCACHED_VERSION=1.0.15
-    - LIBMEMCACHED_VERSION=1.0.14
-    - LIBMEMCACHED_VERSION=1.0.10
-    - LIBMEMCACHED_VERSION=1.0.8
-    - LIBMEMCACHED_VERSION=1.0.7
-    - LIBMEMCACHED_VERSION=1.0.6
-    - LIBMEMCACHED_VERSION=1.0.2
-    - LIBMEMCACHED_VERSION=0.53
-    - LIBMEMCACHED_VERSION=0.49
-    - LIBMEMCACHED_VERSION=0.44
+    - LIBMEMCACHED_VERSION=1.0.18 # Debian Jessie / Ubuntu Xenial
+    - LIBMEMCACHED_VERSION=1.0.16 # RHEL / CentOS 7
+    - LIBMEMCACHED_VERSION=1.0.8  # Debian Wheezy / Ubuntu Trusty
+    - LIBMEMCACHED_VERSION=1.0.2  # Ancient
+    - LIBMEMCACHED_VERSION=0.53   # Ancient
+    - LIBMEMCACHED_VERSION=0.49   # Ancient
+    - LIBMEMCACHED_VERSION=0.44   # Ancient
 
-services:
-  - memcached # will start memcached
+addons:
+    apt:
+        packages:
+            - sasl2-bin
+            - libsasl2-dev
+            - libevent-dev
 
 before_script:
     - ./.travis/travis.sh before_script $LIBMEMCACHED_VERSION
 
 script:
     - ./.travis/travis.sh script $LIBMEMCACHED_VERSION
+
+cache:
+    directories:
+    - $HOME/cache