Add build script

circle.yml

@@ -1,10 +1,10 @@
 machine:
   node:
-    version: 5.2.0
+    version: 5.5.0
 
 dependencies:
   pre:
-    - npm install
+    - scripts/build
 
 test:
   override:

scripts/build

@@ -0,0 +1,14 @@
+#!/bin/bash
+
+if [ -z "$NVM_DIR" ]
+then
+    NVM_DIR="~/.nvm"
+fi
+
+. $NVM_DIR/nvm.sh
+nvm install
+nvm use
+
+set -e
+
+npm install