Graceful shutdown (#16)

* Add package-lock.json

* Add myself to contributors (so folks know who to blame) ;)

* Initial automatic npm audit fix; all tests passing

* Results of npm audit fix --force; all tests passing

(But test not exiting. Same behaviour as I see on Site.js with instant instead of Express static. Will sort out later by implementing graceful shutdown as I believe it is due to lack of garbage collection of the file system watcher.)

* Update supertest to latest; now at zero npm audit vulnerabilities

* Replace deprecated prepublish npm task with prepare

* Update filewatcher to latest version; all tests passing

* Bump version

* Clean up on shutdown (when asked manually and/or if app is killed)

* Ensure cleanUp/graceful shutdown is only active if not bypassed

* Ensure cleanUp() method exists whether bypass is requested or not

* ci: update node version to lts/*

.travis.yml

@@ -1,3 +1,3 @@
 language: node_js
 node_js:
-  - 0.10
+  - lts/*

lib/index.js

@@ -3,6 +3,7 @@ var sendevent = require('sendevent')
   , serve = require('./serve')
   , stack = require('stacked')
   , filewatcher = require('filewatcher')
+  , Graceful = require('node-graceful')
 
 // timestamp to detect server-restarts
 var startup = Date.now()
@@ -45,10 +46,23 @@ module.exports = function(root, opts) {
 
     if (root && opts.watch !== false) {
       var urlsByFile = {}
-        , watcher = filewatcher({ delay: opts.delay })
+
+      fn.watcher = filewatcher({ delay: opts.delay })
+
+      // Stop the file system watcher so apps can exit gracefully when
+      // terminated by Ctrl+c (SIGINT) or a polite termination request (SIGTERM).
+      // You can also call the cleanUp() function directly to handle housekeeping
+      // in your own server (e.g., when it is asked to close).
+      fn.cleanUp = function (done) {
+        fn.watcher.removeAll()
+        done()
+      }
+      Graceful.timeout = 3000
+      Graceful.on('SIGINT', fn.cleanUp)
+      Graceful.on('SIGTERM', fn.cleanUp)
 
       // when a file is modifed tell all clients to reload it
-      watcher.on('change', function(file) {
+      fn.watcher.on('change', function(file) {
         fn.reload(urlsByFile[file])
       })
 
@@ -62,10 +76,20 @@ module.exports = function(root, opts) {
           if (!re.test(path)) return
           urlsByFile[path] = this.path
           this._maxage = 0
-          watcher.add(path)
+          fn.watcher.add(path)
         }}
       })
     }
+  } else {
+    // Bypass requested.
+
+    // Create a noop cleanUp() method so that it can be called without
+    // having the calling app having to check for whether we are running
+    // in production mode or not.
+    fn.cleanUp = function (done) {
+      // Do nothing on purpose.
+      done()
+    }
   }
 
   if (root) {