Merge pull request #1 from zqzhang/zqzhang/license

Add License file
[Xwalkdriver] Sometimes xwalk not reachable

The issue caused by the Crosswalk devtools version changed.
When get url response from localhost://localport/json/version.
It changed from "Browser": "Version/4.0" to "Browser":
"Chrome/36.0.1985.18".
This case is not included in before.

BUG=XWALK-2077