Add Node.js 12 to CI Services (#199)

diff --git a/.travis.yml b/.travis.yml
index 9e90abb..f73bcdf 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -4,8 +4,9 @@
   depth: 10
 
 node_js:
-  - "8"
-  - "10"
+  - 8
+  - 10
+  - 12
 
 install:
   - cd ..
diff --git a/appveyor.yml b/appveyor.yml
index 1b58170..9032c6b 100644
--- a/appveyor.yml
+++ b/appveyor.yml
@@ -2,8 +2,9 @@
 # http://www.appveyor.com/docs/appveyor-yml
 environment:
   matrix:
-  - nodejs_version: "8"
-  - nodejs_version: "10"
+  - nodejs_version: 8
+  - nodejs_version: 10
+  - nodejs_version: 12
 
 install:
   - ps: Install-Product node $env:nodejs_version