datastore: remove devDeps from deps

Author: stephenplusplus

package.json

@@ -52,10 +52,8 @@
   "dependencies": {
     "@google-cloud/common": "^0.4.0",
     "arrify": "^1.0.0",
-    "async": "^2.0.1",
     "concat-stream": "^1.5.0",
     "create-error-class": "^3.0.2",
-    "deep-strict-equal": "^0.2.0",
     "extend": "^3.0.0",
     "is": "^3.0.1",
     "lodash.flatten": "^4.2.0",
@@ -65,6 +63,8 @@
     "split-array-stream": "^1.0.0"
   },
   "devDependencies": {
+    "async": "^2.0.1",
+    "deep-strict-equal": "^0.2.0",
     "mocha": "^3.0.1",
     "proxyquire": "^1.7.10",
     "through2": "^2.0.0"