Feature/field interpolation

[sssoja]

What changes have you made?

• installed dependencies for Lodash and Mustache
• abstracted the interpolation logic from replybot to render dynamic values in the fields
• adapted the getDynamicValue function so that it works for the web survey
• set up the unit tests for getDynamicValue, _interpolate and interpolateField
• moved the biz logic into ResponseStore by creating a new method named interpolationCheck
• changed the scope of qa at the component-level in order to make it accessible for interpolation – it now exists outside of the handleSubmit function

Which issue(s) does this PR address?

76

How to test

• npm test to check that all tests are passing
• npm run dev on localhost:5000 to submit test answers to the survey
• when landing on a question that requires a dynamic value the question should correctly interpolate by rendering with a previously-submitted answer