Set NodeJS 8 as a required toolset

.appveyor.yml

@@ -1,7 +1,7 @@
 init:
   - git config --global core.autocrlf true
 install:
-   - ps: Install-Product node 8.4.0 x64
+   - ps: Install-Product node 8 x64
 branches:
   only:
     - master

.travis.yml

@@ -5,6 +5,7 @@ env:
   global:
     - DOTNET_SKIP_FIRST_TIME_EXPERIENCE: true
     - DOTNET_CLI_TELEMETRY_OPTOUT: 1
+    - TRAVIS_NODE_VERSION: 8.9.3
 addons:
   apt:
     packages:
@@ -13,16 +14,14 @@ mono: none
 os:
   - linux
   - osx
-osx_image: xcode8.2
+osx_image: xcode9.2
 branches:
   only:
-    - master
-    - release
     - dev
-    - /^rel\/.*$/
     - /^release\/.*$/
     - /^(.*\/)?ci-.*$/
 before_install:
+  - nvm install $TRAVIS_NODE_VERSION
   - if test "$TRAVIS_OS_NAME" == "osx"; then brew update; brew install openssl; ln -s /usr/local/opt/openssl/lib/libcrypto.1.0.0.dylib /usr/local/lib/; ln -s /usr/local/opt/openssl/lib/libssl.1.0.0.dylib /usr/local/lib/; fi
 script:
   - ./build.sh

korebuild.json

@@ -1,4 +1,10 @@
 {
   "$schema": "https://raw.githubusercontent.com/aspnet/BuildTools/dev/tools/korebuild.schema.json",
-  "channel": "dev"
+  "channel": "dev",
+  "toolsets": {
+    "nodejs": {
+      "required": true,
+      "minVersion": "8.0"
+    }
+  }
 }