[WRT] Support chrome style extension management

[WRT] Support chrome style extension management

There has been an extension to inject js logic to app.
This supports chrome style extension as well.
The chrome style extension consists of background(event page),
content script, and manifest.json.

Now, two types of extensions are supportive:
one for injection style extension and another for chrome style extension.

Change-Id: Ie37f830d0a3856e8bebba4332bd354dc1f9840fb
Signed-off-by: Youngsoo Choi <kenshin.choi@samsung.com>