[WebUI][LogSearchView] open new window when searching

Related to #824 behavior change.

Currently, link(s) which is linked to `LogSearchSystems` is opened in watching page.
And, when users submit `LogsearchSystems` button, users are forced to be transferred to `LogSearchSystems` (For now, `Groonga Admin`) Web UI.
I think that it is not good because user want to go back to Hatohol client page.
How about using
```js
    window.open(url)
```
instead of
```js
    window.open().location = url
```
?