Don't use two classes XWalkUIClientImpl and XWalkResourceClientImpl.

Both 2 classes are removed out of Crosswalk core library. Use
the public classes XWalkUIClient and XWalkResourceClient.

BUG=https://crosswalk-project.org/jira/browse/XWALK-1481
Merge pull request #105 from yongsheng/master

Don't use two classes XWalkUIClientImpl and XWalkResourceClientImpl.