fix(postinstall): use node, more conditionals (#520)

* fix(postinstall): use node, more conditionals

Closes #516

* chore: move fs-extra to devDependencies

build/utils/postinstall.js

@@ -0,0 +1,15 @@
+var fs = require('fs')
+
+if (fs.existsSync(".git/hooks")) {
+	let commitMsg = '.git/hooks/commit-msg'
+	if (!fs.existsSync(commitMsg)) {
+		let angularPrecommit = "./node_modules/angular-precommit/index.js"
+		if (fs.existsSync(angularPrecommit)) {
+			var fsExtra = require('fs-extra')
+			fsExtra.copy(angularPrecommit, commitMsg, (err) => {
+				if (err) throw err
+				console.log("Installing git pre-commit hook")
+			})
+		}
+	}
+}

package.json

@@ -52,7 +52,7 @@
     "test-fast": "grunt test-fast",
     "version": "node build/sri-update",
     "prepublishOnly": "grunt build && node build/sri-update --validate",
-    "postinstall": "./bin/postinstall.sh",
+    "postinstall": "node build/utils/postinstall.js",
     "release": "standard-version"
   },
   "devDependencies": {
@@ -65,6 +65,7 @@
     "chai": "~3.5.0",
     "clone": "~1.0.2",
     "dot": "~1.0.3",
+    "fs-extra": "^4.0.1",
     "grunt": "^1.0.1",
     "grunt-babel": "^6.0.0",
     "grunt-contrib-clean": "^1.0.0",