Update .travis.yml

Author: shabbyrobe

.travis.yml

@@ -4,27 +4,26 @@ before_install:
   - git submodule update --init
   - composer install
 
+# using multiple php versions in the build matrix yields this error:
+# phpenv global ["hhvm-3.3", "hhvm-3.6", "hhvm-3.9", "hhvm-3.12", "hhvm-3.15", "hhvm-3.18", "hhvm-nightly", "nightly", "7.1", "7.0", "5.6", "5.5", "5.4"] 2>/dev/null
+# [hhvm-3.3, hhvm-3.6, hhvm-3.9, hhvm-3.12, hhvm-3.15, hhvm-3.18, hhvm-nightly, nightly, 7.1, 7.0, 5.6, 5.5, 5.4] is not pre-installed; installing
+# hhvm-3.6,: command not found
 matrix:
   include:
-    - dist: trusty
-      php:
-        - hhvm-3.3
-        - hhvm-3.6
-        - hhvm-3.9
-        - hhvm-3.12
-        - hhvm-3.15
-        - hhvm-3.18
-        - hhvm-nightly
-        - "nightly"
-        - "7.1"
-        - "7.0"
-        - "5.6"
-        - "5.5"
-        - "5.4"
-
-    - dist: precise
-      php:
-        - "5.3" 
+    - { dist: trusty, php: [ "hhvm-3.3" ] }
+    - { dist: trusty, php: [ "hhvm-3.6" ] }
+    - { dist: trusty, php: [ "hhvm-3.6" ] }
+    - { dist: trusty, php: [ "hhvm-3.12" ] }
+    - { dist: trusty, php: [ "hhvm-3.15" ] }
+    - { dist: trusty, php: [ "hhvm-3.18" ] }
+    - { dist: trusty, php: [ "hhvm-nightly" ] }
+    - { dist: trusty, php: [ "nightly" ] }
+    - { dist: trusty, php: [ "7.1" ] }
+    - { dist: trusty, php: [ "7.0" ] }
+    - { dist: trusty, php: [ "5.6" ] }
+    - { dist: trusty, php: [ "5.5" ] }
+    - { dist: trusty, php: [ "5.4" ] }
+    - { dist: precise, php: [ "5.3" ] }
 
   allow_failures:
     - php: "nightly"