Update Travis build matrix to include PHP 7.1, SS 3.5, 3.6 and 3.x-dev explicitly

.travis.yml

@@ -11,15 +11,13 @@ php:
   - 5.3
   - 5.4
   - 5.5
-  - 5.6
-  - 7.0
 
 before_install:
   - pip install --user codecov
 
 env:
   global:
-    - DB=MYSQL CORE_RELEASE=3.1
+    - DB=MYSQL CORE_RELEASE=3.5
     - MODULE_PATH=comments
 
     # Set to 1 in the matrix to enable code coverage
@@ -29,15 +27,13 @@ matrix:
   include:
     - php: 5.6
       #CommentsListTest breaks with this env: DB=MYSQL CORE_RELEASE=3.2 COVERAGE=1
-      env: DB=SQLITE CORE_RELEASE=3.2 COVERAGE=1
+      env: DB=SQLITE CORE_RELEASE=3.5 COVERAGE=1
+    - php: 7.1
+      env: DB=MYSQL CORE_RELEASE=3.6
     - php: 5.6
+      env: DB=PGSQL CORE_RELEASE=3.5
+    - php: 7.1
       env: DB=MYSQL CORE_RELEASE=3
-    - php: 5.6
-      env: DB=MYSQL CORE_RELEASE=3.1
-    - php: 5.6
-      env: DB=PGSQL CORE_RELEASE=3.2
-  allow_failures:
-    - php: 7.0
 
 before_script:
   - phpenv rehash