specifying backbone 0.9.10

(since it doesn't seem like we're trying to have `master` work in older versions of backbone)
Merge pull request #246 from philfreo/patch-1

Specify Backbone.js 0.9.10 as the minimum required version.
Bump version to 0.7.1; this version is ONLY COMPATIBLE WITH BACKBONE >= 0.9.10!
Provide details in the console when the 'Cannot instantiate more than one Backbone.RelationalModel with the same id per type' error is thrown