Update RESThub Backbone stack to 2.1.2
fix dependency problem (underscore-string) in populate-model tests that prevent tests to run
Merge pull request #125 from bmeurant/master

fix dependency problem in tests
Merge branch 'master' of http://github.com/resthub/resthub-backbone-stack
Rollback to Backbone 1.0
Patch from
https://github.com/gsamokovarov/backbone/commit/3bfbcd4123a19f9ec31c5d64d3d4322140adc2fa
Fix issue #127: populateModel and Backbone.Validation