Fixes #10: Run custom script like npm-run-scripts

# Why chest-run-scripts?
A command rapper required usage

## Problem:
+ case(grunt || gulp) write usage
+ Others: npm-run-scripts, make, bash, etc...
+ difficult to write usage
+ Challenging to ensure backward compatibility for commands

## Usage 
```
$ cat .chst/chest.json
{
  "scripts" : {
    "start" : {
      "usage": "start node server.js"
      "run": "node server.js"
  }
}

$ chest scripts
Scripts:
    chest run start: start node server.js

$ chest run start
```