Merge pull request #195 from wp-cli/update/wp-cli-2-12

Require `wp-cli/wp-cli` v2.12

Author: swissspidy

composer.json

@@ -7,7 +7,7 @@
   "authors": [],
   "require": {
     "php": ">=5.6",
-    "wp-cli/wp-cli": "^2.5"
+    "wp-cli/wp-cli": "^2.12"
   },
   "require-dev": {
     "wp-cli/wp-cli-tests": "^4"