Adding 'using' stmt for Newtonsoft.Json;

The JsonProperty attributes being added in the TodoItem class definition (~line 124) require it.
Merge branch 'patch-1' of https://github.com/jgoliver/azure-content into 6-2-14
#1783 pulling in changes to resolve merge issue
Merge pull request #1851 from tysonn/6-2-14

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