Add foreign-store
Add foreign-store

Just so that we can call DevelMain.update from GHCI -- this turns out
to be better than running `yesod devel`, because time waiting for
recompilation is considerably shortened.

Downside: don't know how to set `-DDEVELOPMENT`, therefore static
assets are picked up per `!DEVLOPMENT` configuration.  In theory,
doing a `:set -DDEVELOPMENT` in ghci should work; in practice, it
doesn't.

sajith/betty-web