Allow discovery version ^0.7

Nyholm · Nyholm · commit f873646bf37b · 2016-01-19T17:22:23.000+01:00
diff --git a/composer.json b/composer.json
@@ -17,7 +17,7 @@
     "require": {
         "php": ">=5.4",
         "php-http/httplug": "^1.0",
-        "php-http/discovery": "~0.6.4",
+        "php-http/discovery": "~0.6.4|^0.7",
         "guzzlehttp/guzzle": "^5.1"
     },
     "require-dev": {
