Merge pull request #75 from drzraf/feature/composer-installers-version

support modern version of composer/installers, fix #63

Author: joehoyle

composer.json

@@ -10,7 +10,7 @@
     ],
     "require": {
         "php": ">=5.4",
-        "composer/installers": "~1.0"
+        "composer/installers": "^1.0|^2.0"
     },
     "require-dev": {
         "humanmade/coding-standards": "^0.5.0",