Add TabLimitException

Raises error when more tabs per page than can handle
getting errors at
undefined method `any?' for #<Page:0x007fb916380488>
Rails.root: /Users/trendsettermm/Sites/fg2app
/api/v1/tabs/1

lib/ownable.rb:38:in `ownerable_is_owner?'
lib/ownerable.rb:21:in `owner_of?'
lib/ownable.rb:8:in `ownerable_type_of'
app/models/ability.rb:28:in `block in initialize'