provide livereload 'r' (restart option) to reload from root of app in CLI 3.x

CLI 3.x dropped the hot key command in terminal 'r' to perform the live reload from the root of the app (location.hash = ""). A live reload of the current page, resulting from a change to watched file, can leave the app in an consistent state thus requiring full reload. We need an option to restart the app at the root. I find the loss of this feature to be most problematic for Ionic v1 projects.

**Steps to Reproduce:**

1. ionic serve | ionic run --lc ios | or any other live reload command
2. navigate into your app so not at root page
3. touch a watched file
4. app reloads at current page (location.hash preserved)

**Output:**

CLI has no hot key 'r' to restart the from the root URL (location.hash=""). My work around is to type location.hash="" into the browser debugger.

Bumming.

**My `ionic info`:**

global packages:

@ionic/cli-plugin-proxy : 1.3.2
@ionic/cli-plugin-proxy : 1.3.2
@ionic/cli-utils : 1.5.0
Cordova CLI : 7.0.1
Gulp CLI : not installed globally
Ionic CLI : 3.5.0

local packages:

@ionic/cli-plugin-cordova : 1.4.1
@ionic/cli-plugin-gulp : 1.0.2
@ionic/cli-plugin-ionic1 : 2.0.1
Cordova Platforms : android 6.0.0 ios 4.4.0
Ionic Framework : ionic1 1.3.3

System:

Node : v7.4.0
OS : macOS Sierra
Xcode : Xcode 8.3.3 Build version 8E3004b
ios-deploy : 1.9.0
ios-sim : 5.0.13
npm : 4.1.1

**Other Information:**

Start with the Ionic CLI live-reload command and its terminal hot-key handling, then reproduce the behavior with `ionic serve` by navigating away from the root and touching a watched file. The change is done when an `r` action reloads the app with `location.hash` cleared and the existing live-reload behavior remains intact.

由索引模型根据 Issue 内容生成。