Updates that remove features and improve user experience.
Adds warnings for trying to install packages without (purescript/psc-package#126 by @Dretch)
Filters "installing" messages for build (purescript/psc-package#130 by @Dretch)
Adds options for limiting jobs for install (purescript/psc-package#127 by @vladciobanu)
Per purescript/psc-package#121, removes the confusing misfeature "add-from-bower", which led to many users thinking this command was for adding "extra-deps" like Stack. See the thread for details on how you could readily replace this command if you used it before.
