build: peer dependency for material-examples package (#6165)

* Adds peer dependencies for the CDK and Material to the examples package. This ensures that the API that is used in the examples is always compatible with the current installed version of the CDK or Material.

Author: devversion

src/material-examples/package.json

@@ -23,9 +23,11 @@
   },
   "homepage": "https://github.com/angular/material2#readme",
   "peerDependencies": {
+    "@angular/cdk": "0.0.0-PLACEHOLDER",
     "@angular/core": "^4.0.0",
     "@angular/common": "^4.0.0",
-    "@angular/http": "^4.0.0"
+    "@angular/http": "^4.0.0",
+    "@angular/material": "0.0.0-PLACEHOLDER"
   },
   "dependencies": {
     "tslib": "^1.7.1"