[DAEMON-124] "gulp check" no longer works properly since switching to workspaces

Since Yarn workspaces have been enabled, gulp check is no longer working properly. It checks to see what is installed in the package's node_modules instead of the top-level workspace node_modules. Since it doesn't find a particular dependency installed, it says every package is not installed. While fixing this, we should also make it more parallel so that it can compute the security and package update checks at the same time. We may also need/want to come up with a more robust way of checking integrity. yarn check --integrity doesn't work well with Lerna.