Update gems.
Include backbone-pageable
Revert "Include backbone-pageable"

This reverts commit 11c549a00771d33989784822a3e06dcd0f007192.
backbone-pagination implementation

This actually brings backbone-pagination into the mix.

- the json response has been modified to also include pagination information
- the Posts collection has been updated to be a "PageableCollection" thanks to backbone-pagination.
-- backbone-pagination requires a specific JSON format that is basically an Array with 2 elements, an Object with pagination info and an array of the normal backbone.js response flavor.  This mixed type array is awkward to create with jbuilder so I created a different json structure and over wrote PageableCollection's parseState and parseRecords.
Get isotope out of the way for now.
vendored backbone-pageable
Add state and query params