Update composer version requirements

Author: danhunsaker

composer.json

@@ -1,21 +1,23 @@
 {
     "name": "danhunsaker/bcmath",
     "description": "PHP bcmath as a static class, with several enhancements.",
+    "keywords": ["bcmath", "large number"],
+    "license": "MIT",
+    "authors": [{
+        "name": "Daniel Hunsaker",
+        "email": "[email protected]"
+    }],
     "require": {
-        "ext-bcmath": "^0.0.0"
+        "php": "^5.4|^7.0",
+        "ext-bcmath": "*"
     },
     "require-dev": {
         "behat/behat": "^3.0",
         "henrikbjorn/phpspec-code-coverage": "^2.0",
         "phpspec/phpspec": "^2.4",
-        "phpunit/phpunit": "^5.2",
-        "rmiller/behat-spec": "^0.3.0"
+        "phpunit/phpunit": "^5.0",
+        "rmiller/behat-spec": "^0.3"
     },
-    "license": "MIT",
-    "authors": [{
-        "name": "Daniel Hunsaker",
-        "email": "[email protected]"
-    }],
     "autoload": {
         "psr-4": {
             "Danhunsaker\\": "src/"