mcf: Call git submodule sync before updating submodules

* We've changed submodule URLs in:
  b4a9ca0a9b76c50307c8f09d95c60e3cce7fcf4d
  658121f80563ae61db0e68d7d07d6fecd3baeb0a
* Git will continue to use old URLs in existing checkouts
  until 'git submodule sync' is called.
* It's quick and local changes to submodule URLs are not supported,
  so we can call it on every mcf call.

Open-webOS-DCO-1.0-Signed-off-by: Martin Jansa <martin.jansa@palm.com>
Merge pull request #19 from shr-project/master

git submodule sync