Merge pull request #196 from phpcr/specify-php-version

specify the supported php versions to avoid installing with unsupported versions

Author: dbu

composer.json

@@ -2,6 +2,7 @@
     "name": "phpcr/phpcr-shell",
     "description": "Shell for PHPCR",
     "require": {
+        "php": "^5.6|^7.0",
         "symfony/console": "~2.8|~3.0",
         "jackalope/jackalope": "~1.1",
         "phpcr/phpcr": "~2.1",