allow file include anywhere with respo.json

add new feature to composer.json
```
"include": ["c:/apps/projects","d:/respo","http://localhost/"]
```
and create file respo.json ex:
```
   {
    "repositories": [
        {
            "type": "package",
            "package": {
                "name": "huynguyen/phpserver",
                "version": "5.4.28.0",
                "dist": {
                    "url": "php/php.rar",
                    "type": "rar"
                },
                "source": {
                    "url": "http://github.com/loi-chuanoi/phpserver",
                    "type": "git",
                    "reference": "dev/master"
                }
            }
        }
    ]
  }
```
place in this folder, easy for create new portable repositories and easy include without internet connection