require php extensions in dev only

It is probably too restrictive to have them listed in `require` section in the root `composer.json` file.

Due to the nature of zf1, you may never need some of the extensions, as long as you do not use components which require them. But when you start using them, those components themselves should throw errors that required extensions are not installed.

Moved to `require-dev` to ensure they are installed when running tests on dev/CI.

I've considered adding them to `suggest` section but imo composer might spam too much with irrelevant information, when installing `zf1s/zf1` package.

composer.json

@@ -4,6 +4,9 @@
     "license": "BSD-3-Clause",
     "require": {
         "php": ">=5.3.3",
+        "symfony/polyfill-php70": "^1.19"
+    },
+    "require-dev": {
         "ext-ctype": "*",
         "ext-dom": "*",
         "ext-gd": "*",
@@ -16,13 +19,10 @@
         "ext-spl": "*",
         "ext-xml": "*",
         "ext-zlib": "*",
-        "symfony/polyfill-php70": "^1.19"
-    },
-    "require-dev": {
         "php-parallel-lint/php-parallel-lint": "1.3.0",
         "phpunit/dbunit": "1.3.2",
-        "zf1s/phpunit": "3.7.41",
-        "staabm/annotate-pull-request-from-checkstyle": "1.5.0"
+        "staabm/annotate-pull-request-from-checkstyle": "1.5.0",
+        "zf1s/phpunit": "3.7.40"
     },
     "autoload": {
         "psr-0": {