Make subscriptions for admin path only

[MartinBucko]

First, thanks for making next version of meteor admin. I want help how mutch is possible.I hope we can build amazing meteor admin together :)

• i see in code some subscription wath is not necessary for home page (optimisation) eg. https://github.com/meteor-factory/meteor-admin/blob/master/lib/collections.js#L171 so will be bether to subscribe only in admin location path
• it wil be good to extend router config. For example i have form with select field filed by another collection and i need waitOn subscription to this collection. I see some patch in old meteor-admin in collection config > routes: new: waitOn .. can we apply some thing similar?
• maybe it will be good make old AdminConfig compatible with new version (discussion welcome)