Create project build directory in temp directory

 Added two options:
  --template-dir=DIR  Allow saving of project build to a location
  --template-only        Skip creation of .apk.  Just create template dir
 Modified make_apk_test.py to include option "--template_dir=." in tests

 BUG=XWALK-2394
`'assets', 'www'` to keep the coding style consistency.