Prepare 0.0.4 packagist opencensus/opencensus release (#63)

* Add a composer conflict for > 0.0.4 version of the opencensus extension.

* Change conflict to >= 0.1.0 for the extension

Author: chingor13

composer.json

@@ -24,6 +24,9 @@
         "twig/twig": "~2.0",
         "symfony/yaml": "~3.3"
     },
+    "conflict": {
+        "ext-opencensus": ">= 0.1.0"
+    },
     "suggest": {
         "ext-opencensus": "Enable tracing arbitrary functions.",
         "cache/apcu-adapter": "Enable QpsSampler to use apcu cache.",