composer.json + travis update

- php 7 added in travis
- added latest phpunit version

Author: kokspflanze

.travis.yml

@@ -4,6 +4,7 @@ php:
   - 5.4
   - 5.5
   - 5.6
+  - 7
 
 before_script:
   - composer update --prefer-source

composer.json

@@ -34,15 +34,16 @@
         "imagine/imagine": "0.6.*"
     },
     "require-dev": {
-        "phpunit/phpunit": "4.3.*",
+        "phpunit/phpunit": "~4.3|~5",
         "mikey179/vfsStream": "1.*",
         "squizlabs/php_codesniffer": "1.*",
         "phploc/phploc": "2.*",
         "pdepend/pdepend": "2.*",
         "phpmd/phpmd": "2.*",
         "sebastian/phpcpd": "2.*",
         "theseer/phpdox": "0.7.*",
-        "nikic/php-parser": "<1.2.0"
+        "nikic/php-parser": "<1.2.0",
+        "zendframework/zend-serializer": "~2.5"
     },
     "autoload": {
         "psr-0" : {