- use upstream retry_decorator as external dependency
  + expects: https://github.com/pnpnpn/retry-decorator
  + resolves issues #152
Add retry-decorator as a submodule.
Merge branch 'useRetryDeco' into merge-use-retry-decorator
Update new tests to use new Retry decorator.
Fix duplicate entry created in .gitmodules.

I think the previous version was added manually instead of using
"git submodule add".
Fix setmeta test because tab width changed.