Updated dependencies

- Use PHP 5.5+ **OR** 7.0
- Use `^` notation for all required dependencies.

Author: weierophinney

composer.json

@@ -13,12 +13,10 @@
         }
     },
     "require": {
-        "php": ">=5.5",
-        "zendframework/zend-escaper": "~2.5",
-        "zendframework/zend-validator": "~2.5"
+        "php": "^5.5 || ^7.0",
+        "zendframework/zend-escaper": "^2.5",
+        "zendframework/zend-validator": "^2.5"
     },
-    "minimum-stability": "dev",
-    "prefer-stable": true,
     "extra": {
         "branch-alias": {
             "dev-master": "2.5-dev",
@@ -34,4 +32,4 @@
         "fabpot/php-cs-fixer": "1.7.*",
         "phpunit/PHPUnit": "~4.0"
     }
-}
+}