Optional back button (on questionnaire and instruction pages)

[colbyj]

Right now it is not possible for participants to go back a page in the experiment. This should be something that can be configured within the page list; a "navigate_back" key could be included in the dictionary, and when set to True (default would be False), a button should show up that navigates the participant to /redirect_previous_page so they can go back. It'll be up to the developer of the survey to decide how to include this.