Collect corejam apps CLI commands

[mattvb91]

DerShop provides a bootstrap:db --fauna command. When I add DerShop as a package into my project and run corejam I should see this command as a runnable corejam command in my project.

We could do this by either having each plugin add their cli commands into the corejam {} config inside the package.json of each package or collect all plugins and require them to have their scripts placed inside a cli directory?

@patrickhaug what do you think?