Update supported versions of PHP

Author: ghalse

.travis.yml

@@ -1,14 +1,15 @@
 language: php
 
 php:
-  - 5.4
-  - 5.5
   - 5.6
   - 7.0
+  - 7.1
+  - 7.2
   - hhvm
 
 matrix:
   allow_failures:
+  - php: 7.2
   - php: hhvm
 
 services:
@@ -40,4 +41,4 @@ before_script:
   composer update --dev
 
 script:
-  php vendor/phpunit/phpunit/phpunit.php
+  php vendor/phpunit/phpunit/phpunit

composer.json

@@ -10,11 +10,12 @@
         }
     ],
     "require": {
+        "php": ">=5.6",
         "simplesamlphp/composer-module-installer": "^1.1"
     },
 	"require-dev": {
-        "simplesamlphp/simplesamlphp": ">=1.14",
-        "phpunit/phpunit": "~3.7"
+        "simplesamlphp/simplesamlphp": ">=1.15",
+        "phpunit/phpunit": "~4.8"
     },
     "autoload-dev": {
       "files": ["tests/_autoload_modules.php"]