Update Travis builds to include PHP 7

.travis.yml

@@ -1,32 +1,25 @@
 # See https://github.com/silverstripe-labs/silverstripe-travis-support for setup details
 
-sudo: false
+dist: trusty
 
 language: php
 
-php:
-  - 5.4
-  - 5.5
-  - 5.6
-  - 7.0
-
-env:
-  - DB=MYSQL CORE_RELEASE=3.2
-
 matrix:
   include:
     - php: 5.6
-      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:
+      env: DB=MYSQL CORE_RELEASE=3.6
     - php: 7.0
+      env: DB=MYSQL CORE_RELEASE=3.7
+    - php: 7.1
+      env: DB=PGSQL CORE_RELEASE=3.7
+    - php: 7.2
+      env: DB=MYSQL CORE_RELEASE=3.7
+    - php: 7.3
+      env: DB=MYSQL CORE_RELEASE=3.7
 
 before_script:
   - composer self-update || true
-  - git clone git://github.com/silverstripe-labs/silverstripe-travis-support.git ~/travis-support
+  - git clone git://github.com/silverstripe/silverstripe-travis-support.git ~/travis-support
   - php ~/travis-support/travis_setup.php --source `pwd` --target ~/builds/ss
   - cd ~/builds/ss
   - composer install