transitional frames before and after the app

[lrperlmu]

Mark the transition from study to app and back again.

• transitional frame, after the self-report and before the app welcome, that says something to the effect of "Click next to begin the app. While doing the app, please consider the reference event that you just wrote about"
• remove line about considering the reference event from the app intro
• transitional frame after summary and before self-report, saying thank you for doing the app, now you're going back to the study.
• remove "thank you for doing this activity" out of the summary

[mayacakmak]

Added the transitional frames before and after the app using a simple FromFrame. Refactored the Intro frame and summary frame of the app to remove references to the reference event.