add global tracking and warning on duplicate ties definitions

[gullerya]

The data-tier is built to be able to run multiple times within the same page.
All of the instances will collect the views, and all of them will process and track them, each for it's own.

BUT, the DOM is global, not encapsulated. Therefore, if several data-tier instances will define the same tie key, they'll struggle over the same views and will update them together - mess.

1. Should at least have some warning on the duplication of tie keys globally.
2. Should probably enforce global uniqueness of the tie keys