Use EventuallyConsistentTestTrait for a test (GoogleCloudPlatform#186)

Author: Takashi Matsuo

logging/api/composer.json

@@ -1,10 +1,11 @@
 {
     "require": {
-        "google/cloud": "<2.0",
+        "google/cloud": "~1.0|~0.10",
         "symfony/console": "^3.0"
     },
     "require-dev": {
-        "phpunit/phpunit": "~4.8"
+        "phpunit/phpunit": "~4.8",
+        "google/cloud-tools": "~1.0|~0.5"
     },
     "autoload": {
         "psr-4": { "Google\\Cloud\\Samples\\Logging\\": "src" },