Update php testing versions

Signed-off-by: Joas Schilling <coding@schilljs.com>

.travis.yml

@@ -1,7 +1,8 @@
 language: php
 php:
   - 5.6
-  - 7
+  - 7.0
+  - 7.1
 
 env:
   global:
@@ -51,15 +52,15 @@ script:
 
 matrix:
   include:
-    - php: 5.6
+    - php: 7.0
       env: DB=mysql
-    - php: 5.6
+    - php: 7.0
       env: DB=pgsql
-    - php: 5.6
+    - php: 7.0
       env: DB=mysql;CODECHECK=1
-    - php: 5.6
+    - php: 7.0
       env: DB=mysql;CODECHECK=2
-    - php: 5.6
+    - php: 7.0
       env: DB=mysql;JSTESTS=1
   allow_failures:
     - env: DB=mysql;CODECHECK=2