Modify cldr-import to work with last cldr-25 version

- cldr-25 needs some code modifications, and java 7 to compile.
- Updating Gwt patch to modify cldr data.
- Updated instructions.

Change-Id: I56d61621591138ac2b568ebe8bb2b7d5173bb3d2
Running cldr 25 against a couple of languages -a

Change-Id: Iba75b6067f1f355603b6d212421bf9470466c791