Clean up .gitmodules to remove references to swift

In commit 879e24e964779886bfbc1f3a34a409cc4205531f we removed the
submodules from git but we did not remove the references to these in
.gitmodules.  This commit cleans up .gitmodules to reflect the current
submodule cookbooks that we ship
Merge pull request #746 from rackerjoe/master

Clean up submodules referenced in .gitmodules