Fetch all submodules after clone

From the root of the repo just run:

git submodule update --init

Sync fork

# Step 1 clone fork
git clone git@github.com:<USERNAME>/<FORK-REPO>.git

# Step 2, cd to the repo
git remote add upstream git://github.com/ORIGINAL-DEV-USERNAME/REPO-YOU-FORKED-FROM.git
git fetch upstream
git pull upstream master
git push