implement import entities form json file

JSONファイルによるEntityのインポートの実装。

JSONファイルサンプル
```
[
    {"name":"sample","url":"http://sample.com"},
    {"name":"sample01","url":"http://sample01.com"},
    {"name":"sample02","url":"http://sample03.com"},
    {"name":"sample03","url":"http://sample03.com"},
    {"name":"sample04","url":"http://sample04.com"},
    {"name":"sample05","url":"http://sample05.com"}
]
```