Update Travis distro to precise, except for legacy PHP

.travis.yml

@@ -1,30 +1,29 @@
 language: php
 
 php:
-  - 5.3
+# - 5.3 # requires old distro, see below
   - 5.4
   - 5.5
   - 5.6
   - 7
+  - hhvm # ignore errors, see below
 
 # lock distro so new future defaults will not break the build
-dist: precise
+dist: trusty
 
-# also test against HHVM, but require "trusty" and ignore errors
-# also test lowest dependencies on PHP 5.3 and PHP 7
+# also test lowest dependencies on PHP 7
 matrix:
   include:
     - php: 5.3
-      env:
-        - DEPENDENCIES=lowest
+      dist: precise
     - php: 7.0
       env:
         - DEPENDENCIES=lowest
-    - php: hhvm
-      dist: trusty
   allow_failures:
     - php: hhvm
 
+sudo: false
+
 install:
   - composer install --no-interaction
   - if [ "$DEPENDENCIES" = "lowest" ]; then composer update --prefer-lowest -n; fi